346 MOLLUSCA. 



A mukifidous glandular organ opens behind the genital orifices; 

 there is no vestige of a shell. 



Pleurob. Meckelii, Leve, Diss, de Pleur., 1813(1). The only- 

 species known; from the Mediterranean. 



Aplysia, Lin. (2) 



The margin of the foot turned up into flexible crests, surrounding 

 the back, and even susceptible of being reflected over it; the head 

 supported by a neck more or less long; two superior tentacula ex- 

 cavated like the ears of a quadruped, with two flattened ones on the 

 edge of the lower lip; the eyes above the former. The branchiae are 

 on the back, and consist of highly complicated lamcUce attached to 

 a broad membranous pedicle, covered by a small membranous man- 

 tle, in the thickness of which is a flat and horny shell. The anus 

 opens behind the branchiae and is frequently concealed under the 

 lateral crests; the vulva is before on the right, and the penis pro- 

 jects from under the right tentaculum. The seminal fluid is con- 

 ducted in coitu, from the penis to the vulva by a groove, which ex- 

 tends from one to the other. An enormous membranous crop leads 

 to a muscular gizzard, armed internally with cartilaginous and py- 

 ramidal corpuscles, which is followed by a third stomach sown with 

 sharp hooks, and by a fourth in the form of a caecum. The intes- 

 tine is voluminous, and the animal feeds on fucus. A limpid hu- 

 mour, secreted by a particular gland, and which in certain species is 

 said to be extremely acrid, is exuded through an orifice near the 

 vulva, and from the edges of the mantle oozes an abundant liquid of 

 a deep purple colour, with which, when in danger, the animal tinges 

 the water for a considerable extent. The ova arc deposited in a 

 kind of long, interlaced, glairy net work, of extreme tenuity. In 

 the seas of Europe we have: 



Apl. fas data, Poiret; Rang. Apl., pi. vi, vii. Black; margined 

 with lateral red crests; one of the large species. 



Apl. punctata, Cuv. ; Ann. du Mus. tome II, p. 287, pi. 1, f. 

 2 — 4; Rang, Apl., pi. xviii, f. 2. Lilac, sprinkled with green- 

 ish points. 



(1) It is the genus Pleur obranchidium of Bla'inv., Malac, pi. xliii, f. 3; but not 

 as he thinks the Pleur obranchus tuberculatua of Meckel. 



(2) ATTwa-ia, which cannot clean itself, — a name given by Aristotle to certain 

 Zoophytes. Linnaeus erroneously applied it as above. The animals here spoken 

 of were well known to the ancients, who styled them Sea-Hares, and attributed to 

 them many fabulous properties. 



