20 MOLLUSCA, 



CLASS II. 



PTEROPODA* 



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 placedlike wings 

 on the two sides of the mouth. B\it few and small species are known, 

 all of them hermaphrodites. 



Clio, Lin. — Clione, Pall. 



Have the body oblong, membranous, without a mantle ; head formed 

 of two rounded lobes, whence originate small tentacula ; two small 

 fleshy lips, and a little tongjue in front of the mouth ; the fins covered 

 with 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 with the viscera ; 

 the stomach is wide, the intestine short, and the liver voluminous. 



Clio horealis, L. This species, Avhich is the most celebrated, 

 is found in astonishing numbers in the arctic seas, furnishing, by 

 its abimdance, food for the whales, although each individual is 

 hardly 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 grooves, into six 

 lobes, Encycl. Meth., PI. of the Mollusc, pi. Ixxv, f. J, 2. 



We must place also here the 



CvMRULiA, oi Peron. 



Which have a cartilaginous or gelatinous envelope resembling a 

 galley, or rather a sabot or clog, bristling with small points dis- 

 posed in longitudinal rows. The animal has two large wings 

 composed of a vascular tissue, wliich are its branchiae and fins ; 

 between them, on the open side, is a third and smaller lobe with 



* M. <le Blainville unites my Pteropoda and my Gasteropoda in a single class, 

 which he calls Paracephalophora, of which my Pteropoda form a particular 

 order, under the name of Aporobranchiata. Tliis order is divided into two 

 families ; the Thecosoma, which are furnished with a shell, and the Gymnosoma which 

 are not. 



t The Clio horealis of Pallas (Spicil, X, pi. 1, f. IS, 19), the Clio retiisa of Fabri- 

 cius (Faun. Groen., L., 334), and the Clio lamacim of Phips (Ellis, Zooph., pi. 15, 

 f. 9, 1, 10), of which Gmelin makes as many different species, appear to be this same 

 animal. 



