20 
MOLLUSCA, 
CLASS 11. 
PTEROPODA* 
f 
The Pteropoda, like the Cephalopoda, swim in the ocean, but they 
can neither fix themselves at all, nor crawl, because they have no 
feet. Their organs of locomotion consist of fins jdacedlike wings 
on the two sides of the mouth. But few and small species are known, 
all of them hermaphrodites. 
CliOj Lin . — Clione^ Pall. 
Have the body oblong, membranous, without a mantle ; head tormed 
of two rounded lobes, whence originate small tentacula ; two small 
fieshy lips, and a little tongue in front of the mouth ; the fins covered 
witli a vascular net-AVork which acts as branchiae, the anus and genital 
orifice under the right one. Some authors consider them as possess- 
ing eyes. 
The external envelope is far from being filled Avith the viscera ; 
the stomach is Avide, the intestine short, and the liA^er A'oluminous. 
Clio borealis, L. This species, Avhich is the most celebrated, 
is found in astonishing numbers in the arctic seas, furnishing, by 
its abundance, food for the Avliales, although eacli individual is 
liardly an inch longf. 
Brugiere has observed a larger and not less abundant species 
in the Indian Ocean ; it is distinguished by its rose colour, emar 
ginated tail, and the division of the body, by grooA’es, into six 
lobes, Encycl. Meth., PI. of the Mollusc., pi. Ixxv, f. 1,2. 
We must place also here the 
CA'AfF.uLiA, of Per on. 
Wliich have a cartilaginous or gelatinous eiiA'elope resembling a 
galley, or rather a sabot or clog, bristling Avith small points dis- 
posed in longitudinal roAVS. The animal has tAvo large Avings 
composed of a vascular tissue, Avhich are its branchire and fins ; 
betAveen them, on the open side, is a third and smaller lobe Avith 
* M. de Blainville unites my Pteropoda and my Gasteropoda in a single class, 
vhich he calls Pakacephalophoiia, of -which my Pteropoda form a particular 
order, under the name of Aporobranchiata. This order is divided into two 
families ; the Thecosoma, which are furnished with a shell, and the G>/nincscma w'hich 
are not. 
•f- The Clio borealis of Pallas (Spicil, X, pi. 1, f. 18, 19), the Clio retusa of Fahri- 
cius (Faun. Groen., L., 334), and the Clio lamucinu of Phips (Ellis, Zooph., ]:1. 15, 
f. 9, 1, 10), of which Gmelin makes as many different species, appear to he tliis same 
animal. 
