The dolphin is common around the Tasmanian coast

and in the estuaries of the larger rivers, sometimes ascending

them for many miles from the open sea. During the

currency of the Easter Camp of the Tasmanian Field Naturalists'

Club at Port Arthur we were fortunate in observing a large number of dolphins in Maingon Bay, Tasman's

Peninsula. There were several hundred dolphins in the bay

and their evolutions in the surf were watched with interest

by many of the Naturalists for the greater part of Easter

Monday.

Although it is here assumed that the modern method

of reducing all the smaller dolphins to a single species

(that of the type) is a more or less wise one, it must still



be claimed that such a proceeding leaves certain outstanding

facts unaccounted for. Includes illustrative plates

Lord, Clive Errol

Scott, Herbert Hedley

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PAPERSOF THEROYAL SOCIETY OF TASMANIA1920STUDIES OF TASMANIAN CETAOEA.Part IV.Delphinun delphis(The Common Dolphin.)ByH. H. Scott (Curator, Victoria Museum, Launceston)andOlive E. Lord (Curator, Tasmanian Museum, Hobart).Plates I.-V..(I 12th April, 1920.)As with other members of the Cetacea the synonymyof thi - i- involved. Beddard (1) states that thefollowing appear identical with Delphinus delphis:I>. major, T). Julvqfasciatus, l>. fosteri, U.janira, />.]). bahdii, 1). moorei, D. walkeri, l>. nova : landice,J), albimanus, /'. marginatvs, l> fuscus, D. souverbianus,I). variegatu8, I>. balteatus, D. aloe ienis, l>. moschutns. Whileagreeing in general terms with this combination of synonymswe wish to qualify it with certain remarks liter in tins [taper.The dolphin is common around the Tasmanian Coastand in the estuaries of the larger rivers, sometimes ascend-ing them for many miles from the open sea. During thecurrency of th Camp of the Tasmanian Field Na-turalists' Club at Port Arthur we were fortunate in observ-(1) Beddard: A Book of Whales (1900), p. 254.2 STUDIES OF TASMAKIAN CETACEA,ing a large number of dolphins in Maingon Bay, Tasman'sPeninsula. There were several hundred dolphins in the bayand their evolutions in the surf were watched with interestby many of the Naturalists for the greater part of EasterMonday. It appeared as if the animals were mating.The greater majority kept out in the waters of the baybeyond the line of breaking ocean combers that brokerank after rank upon the coast. Every now and then, how-ever, a score or more would come dashing towards theshore, their outlines showing clearly in the incomingbreaker. Just at the moment the wave broke and it ap-peared as though the dolphins would be cast against therocks or flung far up on the sandy shore, they would turnsuddenly, dive through the crest of the breaker, springseveral feet in the air, and once more swim seawards.Such a sight needs to be actually observed before onefully realises the immensity of the swimming power pos-sessed by these aquatic mammals. The enormous forceof the breaking waves, the various cross currents and un-dertows incidental to such a surf seemed to have noeffect upon the evolutions of the dolphins. Althoughaccustomed as we were to observe the swimming powerspossessed by these animals from vessels and on otheroccasions from time to time, yet it needed such an observa-tion as the foregoing to fully realise the power of theseanimals in their natural element. (See Plate I. and textfig. 1.)i;v H. II. BCOTT AN I) CLI\ K. E. LOKD. «JEXTERNAL CHARACTERS.Although it is here assumed that the modern methodof reducing all the smaller dolphins to a single spi(that of the type) is a more or Uss wise one, it must >t i 11bo claimed that such a proceeding haves certain outstand-ing facts unaccounted for. In a word such a spedthat of "Delphinit8 fosteri," having apparently will mark-id external characl rs, and some slight skeletal ones, doesnot agree in all resp < t- with the large eight feet dolphinsthat frequent our coasts, and of which we hold a com-plete skeleton, and a set of noUs made upon the animalprior to dissection. Perhaps tin lust that can be dourat present is to regard the better defined spof former classifications as being sub-races, and to -inkin inii, all the ill-defined ones. The mon oni studies theCetacea the mor 1 1 1 conviction grows that we are dealingwith a rapidly evolving order of marine mammals, andwithin certain limits, taxonomy is tentative andlinly unworkable if push d to extremes. We here-with detail th xt rnal appearances of two animals,a mature male of eight feet ii and the other animmature male of six and a half feet in length-Mi i asur ment 9 being includi d.Mntiir, Male.Between the dorsal fin and the In ad the animal wasjet black. From the constriction of the beak to the eyeran a curved black line—outlined and washed with white.( th' eye to a line drawn vertically with the back ofthe dorsal tin was a curved line, above which the animalwas black, and below which the colour shaded from dirtygrey to white In the tail region i deal of irongrey appeared, and it was assumed that, in young animals,the grey, white, and iron grey, would appear as yellow,thus giving rise to such a vernacular name as "yellowsided 'dolphin." The actual flukes of the tail were black.Immaturt Malt.In the arrangement of the Beveral colour areas thisyoung male simulated the adult animal, but the whit ofthe tinderparts was replaced by yellow, or more correctly,yellowish white. This animal came from the DerwentRiver and was as nearly adult, in point of measurement,as nine and a half is to twelve. Smaller animals, fromthe same river, in the collection of the Hobart Museum,show much deeper yellow tinting along the underparts—4 STUDIES OF TASMANIAN CETACEA,thus pretty clearly showing that yellow sided dolphinsare immature animals. Individually, the young male hereunder description manifested two, irregularly oval, whitemarks in the region of the tail, but otherwise conformedto the adult tinting, except in the matter of yellow replac-ing white upon the under parts—as already stated.Food.During the dissection of the adult animal the stomachwas turned out, and found to contain a fair amount ofsemi-digested food, and an enormous number of the hornybeaks of cuttlefish, also a few worms. The immature ani-mal had apparently been feeding upon Echinoderms, aslarge quantities of Spatangus spines were found, and werethe only undigested elements met with.Ribs and Scapula.As the scapulas are frequently misplaced in articu-lated dolphins' skeletons, a measurement was made priorto the removal of the scapulae of the immature animal toexactly fix its position. The numerical result was—fromtip of beak to anterior rim of scapula = 21^ inches whenthe arm was at a right angle to the line of the body. Asa guide to articulation, therefore, the hamular processshould just overlap the edge of the first rib. In thematured dolphin the dorsal ribs (five) that reach thesternum, were retained in natural articulation, to set atrest the exact positions of the tubercula and capitula ineach pair of ribs. It is an excellent plan to keep atleast one such thorax in every comparative collection asit forms a court of appeal when cetacean skeletons arein process of mounting.External Mea.xnrtmrntsName of Measurement15V II. II. SCOTT AND CLIVE E. LORD. ;>During the dissection of these two animals variousdata were collected that are of greater individual thangeneral utility, and they are therefore not detailed in thepresent text. By way of giving a comprehensive survey ofthe skull characters, available to us, a large comparativetablo has been drawn up and is hereunder appended. Twoyoung dolphins in tin collection of the Ilobart Museum,which measure four feet two, and four feet four respectively,are available to us. They were captured in the Derwemt,and prepared by Mr. Arnold of tin Museum SiaiT. Mount-ed specimens are notoriously untrustworthy, as to out-but a curious mobility of the snout from tinstriction upwards suggests an outline that is actually ap-proached in lit' when dolphins are racing ai lullthrough the water. It is, as far as our observations go, aprelude to a thoracic flexure, and a distinct shiver iseen to run from stem to stern of this living ship- -andfollows the enormous caudal effort that compleition. The hiad and thorax of a dolphin immobilethan is commonly sup] nd c phalio, thoracic, andI flexures can be distinctly ol sunlitwhen dolphins in sportive mood are swimming ara ship. (Plato II.)o-a +355 rtt/2 -^ ,_, rt cc oi t^"-I a^as a-5 a-^ a-^fed esco m£! S1 ~ ^i?o~ -~ ^ a 3 aS2S 2 to 3 ""coS_ d .3~-~. «M -lea rH MW ~ <*- »to # co OT £ i~- P -* 52 Sr;* ° S hooi^^ISc com co1-1 mv>io «»*o-2 -£M aa S >-i 3 "" S "" Srf —. "oioo t-loo"'-'* . # H N H OO-* *" -* ~—-co "-"'.-I^S;!C•"a-i.L,— -z — .- -— u.- -. »1-2<WC5GW02_---- - - ~= :•- r - m 2— 5 / -|!.S'S lsrfe= -:= r >— - - - .1 '.- — ' -- - —-- . — - ."/7 =S 3- ; c '" '""•£.B« § - - -1 " - '~"i -1ft |rf--B25c —A -' ->=MS-S §».5 g£^-CsS5— . — — z .•- - -A? li i•_ _ -i = r -3 o S"Sg «*- a,Q -r3.0~l»1f Pi2 2 £ • S «A fto'3 0>J — ^8 STUDIES OF TASMANIAN CETACEA,The Skeleton.The axis and atlas vertebrae are always ankylosed inthese whales, the rest of the cervicals being quite free.The vertebral formula is fairly constant, and may begiven as follows :—Cervicals — 7.Dorsals = 14 (some cetologists say 15).Lumbars = 22.Caudals = 32 = 75—with a maximum of 76.Accidental mutilations of the vertebrae are common, evenamong young animals, owing to the custom of divingunder ships in rapid motion. Such effects usually mani-fest themselves in the shape of exostosis, which may cithersimply cover«the elements involved, or by partial absorp-tion and subsequent accretion, materially alter the contourof the bones. We hold various instances, in our respectivecollections, of these naturally healed wounds. The truelumbar vertebrae are devoid of zygapophyses, but theyappear in a functionally reduced state on the chevron-bearing portion of the caudal series;, having doubtlessreference to muscular attachment areas rather than any-thing else. The neural spines slope gradually backwardsthrough half of the dorsal series, assume a recovery in thesecond half, and become vertical in the middle of the lumbarseries—approximately the twenty-eighth vertebra fromthe skull. The chevron-bearing series (or as we mightcall them sacro-lumbars, although usually simply includedin the caudal series) begin by being approximately verti-cal, as regards their neural spines, and end by havingthem pitched at a slope that closely simulates that whichobtains in the middle dorsals. In the two animals dis-sected by me, the following express the sizes of the neu-ral spines, and neurapophyses of the last dorsal thatreaches the sternum, and the largest lumbar of the series ;in other words—the twelfth and twenty-eighth vertebrae,from the skull.KV II. 11. SCOTT ANH OLIVE B. LORD.Comparative Arm Bones.AdultMale10 STUDIES OF TASMANIAN CETACEA.the genus Mesoplodon, as can those of Tursiops, andGlobicephalus, by the less production of the posterior ar-ticular end of the perotic. In this connection Tursioiis isintermediate, showing a more or less style-like extensionthat cuts it off from ear bones of either Delphinus, orGlobicephalus. Mesoplodon, however, of all the whalesnamed, is, at the point indicated, both extended andtruncated. Minor variations of the foramina, etc., are noteasily detailed in anything but an illustrated monograph,although interesting enough to the student.DESCRIPTION OF PLATES.Plate I.This shows a photograph of Maingon Bay, Tasman'sPeninsula, with Cape Raoul in the distance. In the fore-ground can be seen the dolphins springing out of thewave as it broke upon the shore. While this gives someidea of the scene, it does not convey any idea of the num-ber of dolphins in the bay, or the number that could oftenbe seen in the surf at one time. Owing to the very dulllight, and the great rapidity with which the animals per-formed their aquatic evolutions, it was exceedingly diffi-cult to obtain a photograph of the event. Of the manyphotographs, those taken by Mr. F. B. Cane give thebest effect, and we have to thank him for allowing us touse them to illustrate these notes.Plate II.Two young dolphins captured in the River Derwent.The irregularity of outline is due to the mounting. (Tas-manian Museum, Reg. Nos. D591 and 592.)Plate III.Articulated Skeleton of Delphinus delphis (fosteri?)(Tasmanian Museum, Reg. No. D590.).Plate IV.Skull of Delphinus delphis.(Tasmanian Museum, Reg. No. 4680.).Plate V.Skull of Delphinus delphis.(Tasmanian Museum, Reg. No. 4425.).P. & P. Roy Soc. Tas . 1920.P. & P. Roy. Soc. Tas., 1920.P. & P. Roy. Soc. Tas., 1920. Plate III.P. & P. Roy. Soc Tas., 1920. Plate IV.P. & P. Roy. Soc. Tas.. 1920. Plate V.

Studies of Tasmanian Cetacea. Part IV. Delphinus delphis (the common dolphin)

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