54 GASTEROPODA. 



ONCHIDORIS. 



Gills at the end of the back, surrounding the vent ; mantle 

 thick, tuberculous ; tentacles retractile ; foot oval, thick ; organs of 

 generation very distinct, on the right side. 



251. O. tuberClllatllS, sp. nov. Oval, back covered with large 

 flat tubercles ; tentacles pointed ; branchiae plumose ; oral tentacles 

 fused into a veil ; mantle not covering the head, but covering the foot. 

 Dirty yellowish. Length, 4 ; breadth, 2. 



FAMILY ^EOLID^E. 



Animal with papillose gills, arranged along the side of the back ; 

 tentacles sheathless, non-retractile ; skin smooth, no distinct mantle. 



Ovate, dorsal tentacles smooth, oval, slender ; gills simple, cylin- 

 drical, numerous, depressed and imbricated ; foot narrow. 

 All seas. 



* 252. JE. longicauda, Quoy, I.e., ii., p. 288. Elongate, grace- 

 ful, very soft ; apex acute ; tailed ; below brown ; branchise in many 

 series. (Quoy.) 



Cook Strait. 



ORDER PULMONATA. 



Breathing free air in a closed chamber lined with pulnionic vessels, 

 and having an opening closed by a valve on the side. 



Sub-order Inoperculata. 

 No operculum. 



FAMILY ONCHIDIID.E. 



No shell, mantle completely covering the back ; foot straight, much 

 narrower than the mantle. 

 Marine and fresh water. 



ONCHIDELLA. 



Eye peduncles short, buccal appendage lobed ; mantle smooth or 

 granular, without tufts on the back. 



253. O. nigricans, Quoy, Gray, Die/. N.Z., ii., p. 248. Body 

 small, oval, carinated above, uniform black ; apex of tentacles tuber- 

 culate. 



Common on rocks between tide marks. 



PERONIA. 



Eye peduncles short, buccal appendage lobed ; mantle covered with 

 small tentacles and tufts. 



* 254. P. patelloides, Quoy. Body orbicular, conical above, 

 covered with pale yellowish green tubercles, margin of veil perforated 

 with sixteen holes. (Quoy.) 



