28 ONCHIDIID. 
FAMILY—ONCHIDIID/. 
Marine. Animal slug-like. Lingual membrane broad; teeth 
uniform, similar, in numerous straight: transverse rows. Mouth with a 
buccal veil, but no horny jaw. Eyes at the end of non-retractile 
cylindrical peduncles; tentacles none. Mantle coriaceous, large, 
shield-like, entirely covering the back. Respiratory orifice posterior, at 
the right side, under the margin of the mantle. Vent posterior, 
separate from the respiratory orifice. Sexes united ; male organ under 
the right tentacle, female orifice at the posterior extremity of the body. 
Genus, ONCHIDELLA—Gray. 
Eye peduncle short ; buccal appendages lobate. Mantle smooth 
or granular, without tufts or radiating proccesses on the dorsal surface. 
O. patelloides, Quoy and Gaimard ; Voy. Ast., ii., p. 212, 4 15, 
fi 21-23. Body orbicular, somewhat conical above; mantle covered 
with pale yellowish-green granules ; margin of the mantle perforated by 
sixteen white pores. Below yellowish white; tentacles brownish. 
Length about an inch. (Quoy.) 
Tasman’s Bay. Auckland Islands. 
O. nigricans, Quoy and Gaimard; Voy. Ast., ii, p. 214, 4. 15, 
jf 24-26; Chenu, f- 3506. Small, oval; back slightly elevated, broadly 
keeled and black above. ‘Tentacles black, thick and short, rounded 
into a button at their extremity. 
Length, 3 lines. (Quoy.) 
Auckland to Dunedin. 
In some individuals the black color passes into greenish. 
The plate shews that the mantle of this species is granulated as in 
the last. The only difference between the two appears to be the size of 
the swollen extremity of the tentacles. 
O. irrorata, Gould (Peronia); U.S. Ex., Ep. xii., p. 291, f 383- 
Elongated oval, back arched, margins expanded, mottled olive and 
yellow, finely covered with minute, sub-equal granulations, with eight or 
ten elevated, radiating folds or ridges at the margin on each side, which 
extend a little beyond the margin, and give it a dentate appearance. 
Head scarcely protruding beyond the body, dilated at the exterior 
angles ; tentacles short, slender, blue, knobbed, and with an eye-spot 
at the tip. Head above sky-blue, and also the mantle surrounding the 
foot ; margin beneath ochreous. Foot a little more than one-third the 
width of the body. 
Length, 1 inch; breadth, % inch; height, 4% inch. (Gould.) 
Bay of Islands. 
According to Gould, this species differs from O. patel/oides in colour, 
and in the form, and number of the marginal projections. It is probable 
that all three are but varieties of one species. 
