360 
of Psolidium resembling it in shape and scaling will prove to agree 
with Ps. dorsipes also in the character of the intestine. These then 
must remain in the genus Psolidium. The more Cucumaria-Wke 
forms will probably be found to agree with Psolidiella in the cha¬ 
racter of the intestine, and it may well be suggested that they may 
be referred to this latter genus. Not having material for examin- 
ing the question in detail I must content myself with these sug¬ 
gestions, leaving it to others, who are more fortunate in having 
access to material of these forms, to give the proof of my suggestion. 
It is, of course, possible that some of the characters mentioned 
in the description of the species ought really to be included in the 
diagnosis of the genus; this cannot be decided, until more species 
have been shown definitely to belong to this genus. 
17. Psolidiella nigva n. sp. 
Paterson Inlet, Stewart Island; on rocky shore. 6/IV. 1924, (Sten Val¬ 
lin). 3 specimens. 
Largest specimen 23 mm long (tentacles retracted). Shape of 
body Psolus-Wke, with a well marked off ventral sole and a short 
caudal prolongation (Fig. 42). Tubefeet arranged in about four, 
somewhat irregular, crowded series in the radii of the ventral sole; 
in the middle part of the median radius they stand less closely 
and only in two series. At the anterior end of the sole the ventro- 
lateral series of tubefeet turn inwards so as to join those of the 
midventral series, thus forming a definite anterior border of the 
ventral sole. At the posterior end of the sole they are similarly 
arranged, but here a small naked Space is left between the median 
and the lateral series. Through this arrange¬ 
ment of the tubefeet the ventral sole becomes 
very distinctly limited; the limitation is further 
emphasized through the colour, the ventral 
sole with its tubefeet being white, while the 
body otherwise is black. In the body wall 
itself there is no sharp limit between the 
Fig. 42. Psolidiella nigra. ventral sole and the sides of the body. The 
a. From above, b. from 
below. Nat. size. tubefeet of the three ventral radii do not con- 
