i 
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. vit., Mollusg., Mém. x1. 
Sp. Limax cinereus Murty., Limax maximus L., Buatnv. Malacol. Pl. Xxui. 
fig. 5; Srurm Deutschl. Fauna, vi. Heft 2;—Limax ater L., Sturm |. 1. 
Heft 1.; Limax rufus L., Sturm 1. 1. Heft 1., Buarnv. 1. 1. fig. 6, &e. 
Onchidium (BUCHANAN) Cuv., Peronia Buainy. 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 dyxos). See Linn. Trans. Vv. pp. 132—134. 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.1.) 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 Peronit Cuv., Ann. du Mus. v. pp. 37—51, Pl. vi.; Moll., 
Mém. No. 13, Peronia mauritiana Buatny. Malacol. Pl. 46, fig. 7. 
Note.—Peronia ferruginea Luss. lil. de Zool. Pl. 19, is it an Onchidora? 
OrprER III. Cephalopoda. 
Molluses with distinct head, the organs of motion, tentacles or 
arms, crowning the mouth. Body sacciform, open anteriorly. 
Sexes distinct. Respiration branchial. Animals all marine, tes- 
taceous or naked. 
Cephalopods. 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 cesophagus passes and of which the uppermost part covers 
VOL. I. o2 
