270 MR. CHEESEMAN ON NEW OFISTHOBRANCHIATES. [Feb. 19, 



composed of about 22-24 pectinations ; foot oblong, thin and 

 flexible, pale waxy white. 



Shell internal, \ to f inch long, squarish oblong, thin and mem- 

 branous, semitransparent, slightly iridescent, closely marked with 

 somewhat irregular concentric striae or folds ; colour varying from 

 nearly white to pale pinkish or tawny brown. Spire minute, ob- 

 scure, mouth occupying the whole of the undersurface. 



My first specimens of this handsome species were obtained from 

 under stones between tide-marks in Auckland Harbour ; where, 

 however, it is by no means common. Near Waiwera and in some 

 other localities on the Hauraki Gulf it is much more frequently met 

 with. It is easily kept alive iu an aquarium, but is very sluggish in 

 its movements. 



2. PleurobranchjEA nov^-zealandi*, u. sp. (Plate XV. 



fig. 3.) 



Body oval, convex, thick and fleshy, smooth and lubricous to the 

 touch, but the whole surface nevertheless covered with minute 

 puckers and folds. Colour light grey, copiously streaked with 

 irregular anastomosing lines of dark greyish-brown, and sprinkled 

 with numerous minute and almost microscopic white dots. Mantle 

 smooth, not nearly so long as the foot, and not concealing the 

 branchiae, rather broader on the right side ; oral veil broad, extend- 

 ing over and concealing the mouth, in front semicircular, and with a 

 delicate fringed margin, but at each side produced into a short 

 tentacle-like lobe ; mouth large, round, in a state of rest concealed 

 in the sulcus between the oral veil and the foot, but capable of being 

 greatly protruded in a proboscidiform manner ; buccal plates two, 

 large, finely and regularly reticulated or faceted ; odontophore 

 broad, with numerous rows of similar unciform teeth ; tentacles 

 dorsal, wide apart, short and stout, projecting outwards, folded down 

 the outer side, tips obliquely truncate ; eyes minute, black, placed 

 within the integument at the inner bases of the tentacles, quite in- 

 ternal, and not to be seen without dissection ; foot long, extremely 

 flexible, sole pale ashy grey ; branchial plume often over an inch in 

 length, and free for half that distance ; pectinations about 17, 

 finely ciliated ; shell none ; length 2*5 to 3*25 inches. 



This species is very abundant in Auckland Harbour, usually 

 affecting sandy or muddy localities. In the winter and spring 

 months large numbers are often exposed at neap tides, having pro- 

 bably come into shallow water to deposit their ova. Capt. Hutton, 

 of the Otago Museum, informs me that he has collected the same 

 species at Port Nicholson. It is hardy and not easily killed, and 

 may be kept in confinement for a long time. When in a healthy 

 state it is by no means inactive, crawling along by means of its 

 muscular foot much more quickly than might be expected. It has 

 a curious habit of floating in a reversed position, just under the 

 surface of the water ; and I have also observed it swimming by 

 means of rather violent vertical undulations of its body. 



