300 ATLANTIDA. 
Adams, in the delightful narrative of the “ Voyage of the 
Samarang,” says of these animals: 
‘“When fresh taken, I have seen both the Carinarie and 
Atlante swim with their bodies in every position, on their sides, 
on their backs, and with the foot downwards. The Carinarize 
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 Hyalea. 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, heavy skeleton.” 
Carpiapopa, d’Orbigny. 
Ktym.— Cardia, heart, pous, foot. 
Syn.—-Carinaroides, Eyd. and Souleyet. 
Distr.—5 sp. Atlantic. C. placenta, Eyd. (1Ixxxvi, 1-3). 
Shell minute, cartilaginous ; peristome expanded and _ bilobed 
in front, enveloping the spire behind. 
Animal like Carinaria, tail simple, acuminate. 
Famity ATLANTID A. 
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 . xii, 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, glassy, 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, subcylindrical; 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, ly theans 
