16 Records of the Indian Museum. [Worsaiy 
the top. The margin has a prominent anterior tooth flanked by 
four distinct sinuations on each side. No intrathecal ridge exists, 
but the posterior wall bends inwards forming a rectangular bracket 
just above the base of the hydrotheca. The supracalycine sarco- 
thecee are large, almost cylindrical in shape, with a wide aperture, 
and an internal ridge projecting from a fold in their posterior wall. 
They slightly overtop the margin of the hydrotheca. ‘The mesial 
sarcotheca is short, only-about two-fifths the length of the anterior 
profile cf the hydrotheca, to which it is altogether adnate except. 
for a. spout-like tip. Its cavity is interrupted by two processes : 
a button of chitin projects into it from the wall of the hydrotheca a 
short distance before the sarcotheca becomes free, and a septum, 
already described in connection with the internodal ridges, trav- 
erses its proximal end. 
Three cauline sarcothecee occur on each stem internode. Two 
of these are large, resembling the mesial sarcotheca in shape, and 
have a posterior internal ridge: the first lies on the anterior and 
near the proximal end of the internode, the other lies on that side 
of the hydroclade-bearing process which faces the centre of the stem, 
while the third sarcotheca is a mere perforation with slightly raised 
lips on the anterior of the process itself. 
Gonosome.—Attached to the colony itself there occurred no 
reproductive body, but, entangled amongst the fibres at its base, 
a kind of corbula was found. This, in all probability, was really 
part of the colony, for no other Plumularian was contained in the 
same bottle, nor, in fact, were other Plumularians dredged at the 
same station. I shall describe it here on the supposition that gono- 
some and trophosome are one, a supposition which the similarity 
of their minute structures makes a virtual certainty. 
The main body of this peculiar type of corbula consists of a 
hollow cigar-shaped portion within which lie six spherical reproduc- 
tive masses in varying stages of development. Along the sides of 
this cylinder run two tiers of protective leaflets. Both the rows 
in the lower tier contain about Io narrow, tubular leaflets armed 
with up to 16 or 18 nematophores, arranged biserially. In the two 
higher rows 8 or 9 leaflets are present, but they are more strongly 
developed and more irregular in shape than the others, frequently 
broadening out into leaf-like form. They, too, bear marginal 
nematophores but the biserial arrangement is less definite and 
the position of the sarcothecee less regular. In structure the sar- 
cothecee correspond exactly to those which occur on the stem 
internodes. 
All the leaflets stand away from the gonangia-bearing cylinder, 
and all are recurved, those of the upper tier more markedly than 
those of the lower. The lower surface of the cylinder, that is, 
the part corresponding to the keel of a typical corbula, bears longi- 
tudinal chitinous ridges—prolongations of the bases of the lower 
leaflets. On the upper side the gonangia are protected by delicate 
plates of chitin, some of which arise between the bases of the leaflets 
of the upper tier and bend inwards over the gonangia, while others 
