Lista comentada e ilustrada dos Caecidae (Mollusca, Prosobranchia, Mesogastropoda) da Operação Oceanográfica Geomar XII Commented and illustrated list of the Caecidae (Mollusca, Prosobranchia, Mesogastropoda) from Oceanographic Operation Geomar XII

<abstract language="eng">The family Caecidae deserved special attention, among mollusks, because they occurred in more than 50% of studied stations in Oceanographic Operation Geomar XII, which was carried out in northern and southern coasts of Rio de Janeiro and Espírito Santo States (Brazil), respectively. At the time, Caecum brasilicum Folin, 1874, C. aff condylum Moore, 1969, C. circumvolutum Folin, 1867, C. johnsoni Winkley, 1908, C. someri Folin, 1867, C. striatum Folin, 1868, C. venosum Folin, 1867, C. floridanum Stimpson, 1851, C. massambabensis Absalão, 1994, C. butoti Jong & Coomans, 1989, C. ryssotitum Folin, 1867, C. nitidum (Stimpson., 1851) e C. cubitatum (Folin, 1868) were identitíed. C. venosum is reported, for the first time, since its original description, enlarging its occurrence area from Pernambuco to Rio de Janeiro; C. buloti as well, primarily restricted to Dutch Antilles, begins to make part of the Brazilian malacofauna. C. someri and C. butoti were pointed out for being largely non-sintopic with other congeneric species, suggesting that subtile differences in sediment can be responsable for this segregation

Isognomon bicolor (C.B. Adams) (Bivalvia, Isognomonidae): primeiro registro para o Brasil, redescrição da espécie e considerações sobre a ocorrência e distribuição de Isognomon na costa brasileira Isognomon bicolor (C.B. Adams) (Bivalvia, Isognomonidae): first record to the Brazilian littoral, redescription of the species and comments on the occurrence and distribution of Isognomon in the Brazilian coast

<abstract language="eng">The bivalve family Isognomonidae is represented in the Western Atlantic by the living genera Crenatula Lamarck, 1804 and Isognomon Solander, 1786. I. alatus (Gmelin, 1791) and I. radiatus (Anton, 1839) are the only Isognomonidae referred to the Brazilian malacofauna. The present work refers to the first record and geographic distribution of I. bicolor along the Brazilian littoral, and presents a re-description of the species based on shell characters, which include those of the prodissoconch. The occurrence of I. alatus and I. radiatus along the Brazilian littoral could not be confirmed, despite the intensive search for these Isognomonidae from Rio Grande do Norte through Rio Grande do Sul