540 PROF. C. H. o'dONOGHUE : REPORT ON 
middle anterior region. It is usual in this genus for the mantle-folds to be 
folded over the dorsum, but there was no suggestion o£ this in the present 
species. Indeed, these lobes are much more developed than in other members 
of the genus and if folded vsronld far more than overlap. Also their antero- 
lateral corner projects well in front of the head, so giving the animal a 
characteristic appearance not found in other members of the genus. 
Colour. The colour of the preserved specimen is a light brownish fawn 
with a large number of tiny black spots scattered irregularly all over it, and 
the mantle-margin is bordered all round with a black line about 1 mm. wide. 
Professor Dakin informs me that in life the colour was more of a greenish 
fawn with the black markings as in the preserved specimen. 
Dimensions. The length along the middle line was 23 mm., but the antero- 
median corners of the mantle projected about To mm. in front of this. 
Width across the widest point was 21'5 mm. 
Head. .T\\& head is flattened and abruptly rounded at the anterior end. 
On each side is a flattened auriculate tentacle rolled at the lateral margin. 
In the specimen the head was somewhat retracted. 
Foot. The foot is practically indistinguishable, being represented simply 
by the thickening in the antero-median line on the ventral side. It is so 
reduced that it suggests that the animal was incapable of creeping. 
BrancMce. ■ None. 
Radula. The radula is short and uniseriate ; it contains 12-1-4 teeth. The 
tooth has an oblong base with rounded corners, and the upper portion is 
carried on as a long, stout, slightly curved, non-denticulate, almost conical 
spine. The bases of the teeth are closely approximated, so that each spine 
overlaps the whole of the base of the tooth immediately in front of it, and 
about half the next also. The spines lie down upon the succeeding tooth, 
which is slightly hollowed to receive them, save in the front tooth, which is 
almost upright and appears to be the only one in use. 
The dental sac contained twenty or more discarded teeth. Some of these 
are quite small, not a quarter of the length of that in use, so that it would 
appear that they are carried for a relatively long period of time. 
Notes. But one specimen is represented in the collection, obtained from 
the shore of Wooded Island. 
While it is here referred to the genus Placobranchus, it is, as noted above, 
different from the previously described members of the genus in the following 
points : — 
(1) It has non-denticulate teeth. (2) It has a relatively much greater 
extension of the mantle-lobes. (3) It has forward extensions of these lobes. 
Rather than make a new genus, however, it is included here, since in other 
points it agrees closely with the previously known membei-s. 
The large expansions of the mantle and almost total lack of a foot rather 
suggest that it may be a swimming form. The name P. expansa is here 
suggested to call attention to the larae mantle-lobes. 
