Power, G.

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148 REVIEWS varying equipments  under  harsh  working conditions frequently affects the accuracy of the  data,  the discussion  stresses the  problems involved in averaging values and in quality control. For clarity  where many data are available, they have been averaged by var- ious sized areas. Other regions suffer a pau- city of data.  Where  there are  no  data  at all, the blank areas in the highly-coloured pat- terns give the charts a moth-eaten appear- ance. In the horizontal contour charts, surface conditions are omitted; the shallowest con- tour is for 20 m. At this level one chart is presented for summer and one for winter conditions for each of the three variables, T, S ,  and 0. For depth levels of 200 m.  and below, data for all seasons are averaged to- gether. The smoothed  contours of horizontal sec- tions of temperature  values  are  in  whole de- grees Celsius except for the 2,000 m. and 3,000 m. levels, where they are in 05°C. They  are vividly coloured from blue to ma- genta in  2°C. intervals from 0 to  8°C. These irregular contours on an orthographic polar projection  generally  circle the  antarctic con- tinent, with increasing values to  the north. Corresponding projections of salinity sec- tions are contoured in 0.2, 0.1 and 0.05%,, depending on  the depth  of the section. They are coloured at 0.4%, intervals in yellow- brown  tones  which  range from bright yellow to brown red. The  third variable on each  plate  portrays the dissolved oxygen content of the water. Values are contoured in 0.5 ml./l. for all levels and coloured in 1.0 m1.A. intervals. Six shades and tints of green, from a light yellow green to a dark brownish green are used. In the discussion  of the contoured sec- tions, the observed distribution of the vari- ables is explained by eddies or gyres in the circulation,  but no chart shows these  circula- tion  patterns. It would  also  be  helpful to present  some  information on ice, which greatly affects the  other  near-surface vari- ables. The companion  report, Sound Channels in  Antarctic  Waters, includes a brief  gen- eral description  of sound  channels;  their controlling factors; and their presence and seasonality in the Antarctic. The last plate, number 19, presents 10 graphs of the vertical sound speed structure at designated latitudes along the 19"E. meridian for most of the months. Superimposed on each monthly se ries of speed profiles are coloured, dashed lines connecting the axes of the sound chan- nels. Sound  channel  depths  in the Antarctic are interesting in that repeated sections exhibit wide seasonal  variations. In some  cases a sound  channel is shown at two different depths. It makes one wonder  how  much vari- ability is found in the original temperature and salinity data on which the sound speed was  based. The profiles are a little confusing because the sound speed is plotted as increasing to the left, but the scale implies an increase to the right. Furthermore,  the axes  of some sound channels are shown to fall along the surface.  This is not  the  common usage of the term "axis", which is rather thought of as a depth of minimum sound speed occurring at some distance below the surface, permit- ting a channelling of sound by refraction from above, and below. Two polar projec- tions  howing  geographical  distribution of the  speed of sound at  the depth of the sound channel axis, for winter and summer, com- plete the plate. References for  the two  parts, 23 and 9 re- spectively,  afford ample  guidance for  further exploration of the subject. This is an informative, useful and beauti- ful folio. It has fulfilled well its stated aim of data display and will be enjoyed by any- one interested in  the Antarctic. K .  G .  La Fond E.  C. La Fond FRESHWATER  FISHES OF NORTH- WESTERN CANADA AND ALASKA. BY J. D. MCPHAIL and C. C. LINDSEY. Ottawa: Fisheries Research Board of Canada, Bulle- tin 173. 1970. 6% x 9% inches, 381 pages. $8.50. As an introduction,  the  authors  have devoted the first section of this Bulletin to back- ground information. They provide a history of publications on northern  freshwater fishes, an outline of  geological history,  zoogeograph- ical patterns, summary of dispersal routes, details on classification, nomenclature, the scope of the species descriptions, and meth- ods of identifying fishes. The second and by far  the greatest part of the Bulletin consists of keys for  the identification  of  fish families and species and accounts  of 59 species found in the  area  under consideration.  This includes drainages on  the  North American mainland that  are tributaries either to  the Bering Sea, to the Arctic Ocean from Bering Strait, to Hudson Bay or to the west side of Hudson Bay north of 60"N. Also included are St. Lawrence Island in the Bering Sea and is- REVIEWS 149 lands of the Western Canadian Arctic Ar- chipelago.  All  freshwater and anadromous species known from the area are illustrated and  described. Species that only  occasionally enter freshwater in the area or that occupy freshwaters  adjacent to the  area  are included in the keys. The Bulletin concludes with a section on collecting  and  preserving  aimed at encouraging the interested layman to con- tribute  to  our knowledge of the  Ichthyo- fauna of this  little known part of the world. A  bibliography is provided. Although first impressions might  lead  one to suppose  the  scope of this  publication was too limited to be of much general interest, this is not so. The outline of geological his- tory is mainly  concerned  with  glaciation and the  pattern of retreat of the ice following  the last glacial period, the Wisconsin. Of most interest here in terms of the fish fauna are changes in drainage patterns and formation of post-glacial  akes. The zoogeographical section considers the probable dispersal of fish species from three refugia: the Pacific, the Bering and the Mississippi - in which they survived the last glacial maxima. The reconstruction of dispersal  routes and origins of the freshwater fish fauna of Alaska and the  Western Canadian  Arctic is very  plausible and the authors have obviously tried very hard to  be objective. Considering  the  nature of the evidence and the scarcity of collec- tions  from  the  area  they  are  to  be  congratu- lated for  their ingenuity. The keys provided in the  book are simple and well illustrated. By using the methods of identifying fish section, and the glossary, anyone with  a  little  patience  should be  able to  identify any species of freshwater  fish  from the area under discussion. Even the key to the  juvenile  salmonids seems to be workable and these are  particularly difficult to identify. The species accounts are well rounded  and as  complete  as possible. They are  illustrated by beautiful and accurate line drawings, al- most all done by Mrs. Jean Ramsey Maher. A  distribution  map shows localities from which the  authors have  examined specinlens and a  small  inset  map shows the known nat- ural  distribution of each species. Distinguish- ing  characters  are given. A description gives taxonomic  details  uch as counts of gill rakers, fin rays, scales, vertebrae  and  pyloric caecae as well as  notes on  colour  and  sexual dimorphism. The  distribution is described. Taxonomic  notes give information  on nomen- clature and synonyms. Problems that have arisen possibly as a result of speciation in different  refugia and subsequent  intermin- gling of forms are aired where appropriate. A  conservative  approach is taken by consid- ering the resultant forms as complexes, e.g. Coregonus  clupeaformis complex, and Os merus eperlanus complex.  Postglacial dis- persal is described and an account of the biology of the species gives information on habits, age and growth, diet, fecundity and any other information about the species in the  area  that is available.  This is generally  a comment on commercial or native exploita- tion of the species. I have only one regret  about the publica- tion  and  that is that it  did  not  cross  Hudson Bay and include  northern Quebec, Labrador and  the eastern arctic in its scope. It would have required very little more effort to add the  Atlantic  refugia  and  include  this  area. The coloured illustrations are disappoint- ing and do not match up to the otherwise excellent quality of the Bulletin. I hope if the  Fisheries Research Board is to continue using coloured  plates a better  quality of r e  production can be achieved. All in all this is a good book which should find its way onto  the shelves of anyone with any  interest in  northern  freshwater fishes. G. Power GEOLOGIC  MAPS  OF  ANTARCTICA. BY CAMPBELL CRADWCK et al. Antarctic Map Folio Series, Folio  12. New York: American Geographical  Society,  1969-1970. 17 x 11 inches, 23 mops. $12.00. The  publication of “Geologic Maps of Ant- arctica”, which coincided with the SCAR/ IUGS Symposium on  Antarctic  Geology  and Solid Earth Geophysics in Oslo last August (1970), is a  welcome  event for  both  antarctic geologists and those interested in southern hemisphere  paleogeography and biogeogra- phy. The  organisation is such  that  the  basic elements of the geology are  clearly displayed for  the  casual viewer, and yet a closer  exami- nation reveals the most detailed and exten- sive  compilation of antarctic  geological  data to date.  Folio 12, which  was  begun in 1964, was accomplished through the co-operation of 25 geologists from eight countries. The folio includes two groups of maps. The first comprises regional geologic maps, mostly at a  scale of 1: 1,000,000, which cover virtually all the areas of known rock outcrop on the continent. These were com- piled by invited geologists with the fullest knowledge of each region. The second  group comprises four maps of Antarctica  compiled by Dr. Craddock from the regional maps and  other sources. They show, at a scale of 1: 10,000,000, fossil localities, sampling lo- 

Freshwater Fishes of Northwestern Canada and Alaska, by J.D. McPhail and C.C. Lindsey

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Freshwater Fishes of Northwestern Canada and Alaska, by J.D. McPhail and C.C. Lindsey

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