460 MR. S. PACE ON THE ANATOMY OF THE 
The single specimen (the type-specimen) examined by me had 
been dredged off the Kistna coast in the Bay of Bengal * by the 
‘Investigator’ in 753 fathoms. The animal had been extracted 
from its shell before I received it ; and unfortunately, as also in 
the case of P. mirabile, the body-cavity had been cut into and the 
parts somewhat displaced. 
The foot is flattened and elongate, and bluntly pointed pos- 
teriorly ; anteriorly it is truncated and slightly bilobed and bas 
the angles considerably produced. The front margin of the foot 
is prominently duplicated and the cleft is very deep. There is 
no vestige of an operculum or opercular pad and no visible pedal 
pore. The rostral region is not so extensively developed nor so 
specialized as it is in P. mirabile; it is not so cylindrical as it is 
in that species and its terminal disk is smaller and less definite. 
The tentacles, again, are proportionately longer than they are in 
the type-species: and, unlike the condition in the latter, they 
bear prominent black eye-spots, which are situated posteriorly 
upon slight elevations at their bases. The tentacles are disposed 
laterally to the snout, and their axes, if produced, would approxi- 
mately cut that of the rostrum. ‘The slightly thickened mantle- 
margin is continuous right-round the body. The siphon is very 
short and broad, and the mantle-margin forms a wide collar 
around its hase. The penis is large and of complex structure; it 
is placed rather far forward and is not covered by the mantle ; its 
general form is indicated in the figures (Pl. 42. figs. 10 & 11, P.). 
The spermatic duct is broad and unconvoluted ; it 1s completely 
enclosed, and its external opening is at about the middle of the 
lesser curvature of the penis. The body had apparently been 
unpigmented. 
The pallial cavity of this species presents considerable similarity 
to what obtains in P. mirabile; but the hypobranchial gland is 
more definitely developed than it is in that form: there was no 
indication of any coloured secretion. The osphradium is propor- 
tionately considerably larger than it is in P. mirabzle, and its folie 
are nearly equal. The triangular gill-lamine have their shortest 
edge disposed towards the rectum. 
The condition of the introvert apparatus (Pl. 42. fig. 12) is 
less specialized than itis in P. mirabile. As in the latter species, 
the rhynchostome is furnished with a cartilaginous support; but 
the rhynchodeum is less completely subdivided, the transverse 
* Ind. Mar. Survey Station, No. 134. 
