360 ATLANTID^. 



Adams, in the delightful narrative of the " Voyage of the 

 Samai'ang," says of these animals : 



"When fresh taken, I have seen both the Carinarise and 

 Atlantae swim with their bodies in every position, on their sides, 

 on their backs, and with the foot downwards. The Carinarise 

 are swift and rapid in their movements, and dart forwards by a 

 continuous effort, moving their foot and caudal appendage from 

 side to side, as a powerful natatory organ, and do not progress 

 by sudden jerks, like the Atlanta and H3^alsea. The true analogue 

 of the foot of gastropods in Atlanta and Carinaria is the sucking 

 disk, but its use is circumscribed to that of enabling the animal 

 to anchor itself temporarily to floating bodies when fatigued. The 

 shell of Carinaria covers only a small portion of the body, defend- 

 ing the more delicate organs, and in this we see a wise provision for 

 permitting these pelagic mollusks to move freely about, without 

 being encumbered with a dense, heavj'^ skeleton." 



Cardiapgua, d'Orbigny. 

 Etym. — Gardia, heart, poics^ foot. 

 Sy7i. — Carinaroides, Eycl. and Souleyet. 

 Distr. — 5 sp. Atlantic. C. pZacen^a, Eyd. (Ixxxvi, 1-3). 

 Shell minute, cartilaginous; peristome expanded and bilobed 

 in front, enveloping the spire behind. 



Animal like Carinaria, tail simple, acuminate. 



Family ATLANTID^. 



Animal furnished with a well-developed shell, into which it 

 can retire ; gills contained in a dorsal mantle-cavity ; lingual 

 *teeth similar to Carinaria. Dentition ixii, 41). 



Shell symmetrical, discoidal, sometimes closed by an oper- 

 culum. 



Atlanta, Lesueur. 



Syn. — Steira, Esch. 



Distr. — 18 sp. Warmer parts of the Atlantic, Canary Islands. 

 A. turriculata, d'Orb. (Ixxxv, 4, 5). Fossil, 1 sp. Tertiary; 

 San Domingo. 



Shell minute, glass}^, compressed and prominently keeled ; 

 nucleus dextrally spiral; aperture narrow, deeply notched at the 

 keel. Operculum ovate, pointed, lamellar, with a minute, apical, 

 dextrally spiral nucleus. 



Animal three-lobed ; head large, subcj lindrical ; tentacles 

 conical, with conspicuous eyes behind them ; ventral fin flat- 

 tened, fan-shaped, furnished with a small, fringed sucker ; tail 

 pointed, operculigerous. 



" The Atlanta," writes Mr. Arthur Adams, " is quite a sprightly 

 little mollusk, probing every object within its reach, by means 



