MOLLUSCA. 817 



Ground-slug, Path-slug. The mantle is here small and in some contains 

 a calcareous grit, in others a small shell. At .the hinder end of the body is 

 a small aperture, from which adhesive mucous threads proceed. Here 

 the viscera are placed in the body and not in the mantle, as in the snails 

 (Helices}. The internal structure however has much resemblance to that 

 of the Helices; but the calcareous dart and the purse that contains it are 

 here absent. 



These animals live on herbs, fruits, &c., and dwell in moist places. 

 Comp. Cuv. Ann. du Mus. vn., Mollusq., Mem. XI. 



Sp. Limax cinereus MUELL., Limax maximus L., BLAINV. Malawi. PI. XLI. 

 fig. 5 ; STURM Deutschl. Fauna, vi. Heft 2 ; Limax ater L., STURM 1. 1. 

 Heft i. ; Limax rufus L., STURM 1. 1. Heft i., BLAINV. 1. 1. fig. 6, &c. 



Onchidium (BUCHANAN) Cuv., Peronia BLAINV. Tentacles 

 four. Body oblong, creeping, marginate everywhere by thick 

 mantle. (Orifice for the passage of penis under the right tentacle ; 

 vent, respiratory foramen and aperture of female genitals beneath 

 the posterior extremity of mantle. Veil emarginate over the mouth, 

 or two auriform appendages at the sides of mouth.) 



Half a century ago a slug-like animal was first discovered by BUCHANAN 

 in Bengal, on the leaves of Typha elephantina, to which, on account of the 

 many small tubercles on the back, he gave the generic name cited above 

 (derived from 6yKos). See Linn. Trans, v. pp. 132134. The animal dis- 

 covered by B. has not, to my knowledge, been described more particularly 

 by any later observer ; the animals to which CUVIER gave this generic name 

 live in the sea near the shore, and also come on land. According to 

 EHRENBERG (Symbol. physic., Evertebr. i.) there are seen behind on the back 

 arborescent appendages which contract when the animal is on dry land and 

 which may be regarded as gills. This animal may thus form the transition 

 to the Gymnobranchiata and have an affinity to Doris. 



Sp. Onchidium Peronii Cuv., Ann. du Mus. v. pp. 3751, PI. vi. ; Moll., 

 Mem. No. 13, Peronia mauritiana BLAINV. Malacol. PI. 46, fig. 7. 



Note . Peronia ferruginealjKBS. 1H. de Zool. PI. 19, is it an Onchldora? 



ORDER III. Cephalopoda. 



Molluscs with distinct head, the organs of motion, tentacles or 

 arms, crowning the mouth. Body sacciform, open anteriorly. 

 Sexes distinct. Kespiration branchial. Animals all marine, tes- 

 taceous or naked. 



Cephalopoda. These animals present clear vestiges of an internal 

 cartilaginous skeleton. In the head is found, in most, as in Sepia, 

 Loligo and Octopus, a cartilaginous ring, through the aperture of 



which the oesophagus passes and of which the uppermost part covers 



KO 

 VOL. I. 



