A NEW SPECIES OF CAVOLINA, WITH NOTES ON 

 OTHER PTEROPODS 



By WM. H. DALL 

 Curator, Division of Mollusks, U. S. National Museum 



Having had occasion lately to revise the dry- specimens of Theco- 

 somatous Pteropods in the National Museum, in which the collection 

 proved unexpectedly rich, several specimens of a species of Cavolina 

 (=Hyalcea) were found which could not be assigned to any of the 

 recognized species. 



CAVOLINA COUTHOUYI, n. sp. 



Shell of moderate size, colorless, transparent, inflated, widest at 

 the posterior transverse line of the lateral sinuses ; shell in the median 

 line behind blunt, wide, evenly rounded off, with no median spine, 

 the median portion projecting slightly beyond the straight posterior 

 margin of the lateral angles ; ventral plate dome-like, the lateral 

 angles triangular, slightly bent dorsally ; the lateral clamps as usual 

 in the genus, the anterior lip narrow, slightly reflected backward 

 over a rather wide, strong constriction ; surface ornamented with 

 regular, slightly elevated concentric lines, with wider interspaces, 

 which become less wide toward the front; dorsal plate longer, its 

 anterior margin evenly arched over the ventral lip, very slightly pro- 

 duced, with a shallow median, narrow gutter ; sculpture of the back 

 with three subequal, low, radial ribs with shallow, wider inter- 

 spaces, and fine radial striae crossed by incremental lines ; the median 

 rib arching evenly over to the posterior margin of the dorsal lip. 

 Length, 7; width, 7; maximum dorso-ventral diameter, 4.5 mm. 



Fiji Islands, A. Garrett, U. S. Nat. Mus., 110,595; New South 

 Wales, Couthouy, on the Wilkes Exploring Expedition, U. S. Nat. 

 Mus., 18,050. 



This species has the posterior end rounded as in C. longirostris, 

 but the form of the aperture, the sculpture of the back, and the char- 

 acters of the lateral angles form a combination unlike any of the 

 described species. All the specimens are very uniform in character. 



It may be noted that the name of australis (Clio) given by 

 D'Orbigny in 1836 and used in the Challenger Report was used in 

 1792 by Bruguiere for a species now referred to Clione. The later 

 name must therefore he rejected, and for it I would propose the 

 name of Clio antarctica. 



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