52 PTEROPODA. [Thecosomata. 



it. The animal has a ventral pallial cavity, and the fins form a broad 

 disc, on the dorsal margin of which the cephalic portion is laid back. 



The shell of the adult is considerably elongated in a dorse-ventral 

 direction. It is somewhat hollowed out in the form of a boot or 

 slipper, and is more or less broadly open ventrally. It is not homo- 

 logous with the calcareous shell of other Thecosomata. but is the 

 result of thickening of the integument. 



The animal has its visceral portion relatively little developed, 

 and the fin greatly predominates. The cephalic portion is distinct, 

 the lip completely surrounding the mouth. The 2 tentacles are sym- 

 metrical, and the right one is not enclosed in a sheath. The verge 

 is situated on the dorsal surface of the head, in the median line in the 

 adult. 



Genus 1. CYMBULIA, Peron and Lesueur, 1810. 



Cymbnlia, P. & L., Ann. Mus. Hist. Nat. Paris, xv, 00. Type : C. Peroni, 

 de Blainville. 



The animal has a natatory disc of considerable breadth, and a 

 ventral lobe on the foot. The cephalic portion is reflected on the 

 dorsal margin of the fin. but is fixed throughout its length, and con- 

 stricted towards its distal extremity. Jaws are present. Radula 

 having the formula 1 + 1 + 1, the central tooth very broad, laterals 

 with a moderately broad base, unicuspid. 



Shell, or " deutoconch," described as cartilaginous or gelatinous, 

 is elongated in a dorso-ventral direction, and has a moderately elon- 

 gated cavity and a pointed dorsal extremity. The external surface is 

 covered with tubercles arranged in rows parallel to the main axis ; 

 the dorsal extremity is always dilated, and projects more or less 

 markedly. 



1. Cymbulia parvidentata, Pelseneer, 1888. Plate 6, fig. 1. 



Cyrnbulia parvidentata. Pelseneer, Chall. Rep., xxiii, 1888, 99, pi. 2. f. 12, 13. 



Shell slender, proportionally narrower and more elongated than 

 C. Peroni, and exhibiting a constriction towards the middle of its 

 lenoth, the dorsal portion long and pointed ; the spines on the surface 

 of small size ard very uniform even on the borders of the aperture, 

 where they are very large and distinct in C. Peroni. The 2 rows of 

 spines which end in the" ventral points exhibit at their middle a re- 

 entrant angle corresponding to the constriction of the shell. The 

 cavity of the latter is very narrow and of little depth. 



Length, 35 mm. 



An : mal unknown. 



Type in the British Museum. 



Hab Cook Strait (" Challenger "). 



