EOLIS. MOLLUSCA. 69 



Dr R. E. Grant, who found this species in the Frith of Forth, observed, when 

 keeping it in a glass vessel, that it possessed the faculty of emitting distinctly audi- 

 ble sounds. 



Gen. 28. EOLIS, Lam. Limax, Lin. 



Body oblong, terminating in a point posteriorly, slightly convex 

 above ; no mantle ; head short, with four or six tentacula ; 

 branchiae projecting, in the form of scaly plates, papillated, 

 or like cirri, disposed along the back in rows ; anal and ge- 

 nerative orifices on the right side. 



E. Cuvieri, Lam. (L, papillosus, Lin.) Body subovate ; tentacu- 

 la six ; colour brownish, tinged with purple. 3 inches long. In- 

 habits European seas. B. Mont. Lin. Trans, xi. pi. 4, fig. 3. 



Gen. 29- GLAUCUS, Cuv. 



Body elongated, subcylindrical, gelatinous, terminating poste- 

 riorly in a slender subulate tail ; head short, with four coni- 

 cal tentacula, in pairs ; three or four pairs of branchial fins, 

 lateral, opposite, palmated, and digitated at their summit, the 

 posterior ones almost sessile ; orifice of generation and anus 

 disposed laterally. 



G. Forsteri, Lam. (G. Atlanticus, Blumen.) About an inch and 

 half long. Seas of warm climates. An. Mus. xv. pi. 3, fig. 9. 



ORDER V. PTEROPODA. 



No foot for crawling, nor arms for seizing their prey ; two op- 

 posite and similar fins, proper for swimming ; body free, 

 floating. 



The Mollusca of this order are furnished with two opposite fins. They are in ge- 

 neral of small size, without appendages, or very short ones, at the head. Some are 

 furnished with a thin cartilaginous or horny shell. 



Gen. 1. PNEUMODERMON, Cuv. 



Body free, naked, soft, oval ; head distinct ; mouth terminal, 

 with two lips ; two bundles of retractile tentacula at the sides 

 of the mouth ; no eyes ; wings opposite, small, oval, insert- 

 ed on the sides of the neck ; two branchial pinnated lines 

 situated exteriorly in the upper part of the body ; anus late- 

 ral. 



P. Peronii, Cuv. About an inch long. Inhabits Atlantic Ocean. 

 An. Mus. iv. pi. 59. 



Gen. 2. CYMBULIA, Cuv. 



Body oblong, gelatinous, transparent, inclosed in a shell ; head 

 sessile; two eyes, and two retractile tentacula; mouth fur- 

 nished with a retractile proboscis ; two opposite, oval, bran- 



