76 PERCY SLADEN TRUST EXPEDITION 
but in others they are quite near the distal end as figured by Grube (22), ze. they, 
are sub-terminal and similar to those described by Morch in his genus Hucarphus 
(87, p. 378). 
All the spines are provided with interior median basal spines. There is a large 
thoracic membrane and collar, the latter being very ample and much folded ; the ventral 
lobe seems generally to be entire. The branchize, of which there are 16—18 pairs, have 
very long terminal filiform processes. 
The setze are of the usual shape and resemble Gravier’s figures (15, text-figs. 463— 
466), the uncini having 5—7 teeth. The abdomen consists of about 150 segments. 
A thin calcareous tube with conspicuous growth lines containing a very young 
animal of presumably the same species was found firmly grasped by the opercular spines 
of the largest specimen and the scar on the tube looked very much as though it had been 
torn away from the substratum on which it had been growing. The total length of this 
young form is barely 3 mm. and it still retains its original functional operculum with 
a single row of serrations on the left side—the shorter one which was going to develop 
into the first adult functional one with the characteristic shape (Zeleny, 51, p. 934) being 
on the right. It has the ordinary seven thoracic segments but only about 24 abdominal 
ones; the latter have tori containing 12 uncini of the usual shape. Each fascicle of 
ventral setz: consists of three trumpet-shaped ones and one very long fine capillary one. 
The collar setze (fig. 2c) are remarkable in having a coarsely serrated fin-like process at 
the base of the blade instead of the ordinary two processes. I do not know whether this 
could be a stage in the development of such sete. There are five or six in each fascicle 
and the same number of fine capillary ones. 
5. Hydroides bifurcatus, n. sp. (Plate 8, fig. 3). 
Specific characteristics: the opercular funnel has 25 sharp pointed teeth round its 
edge and a central crown of seven curved spines; six of these are bifid at the distal end 
giving two sharp outwardly directed lateral teeth; each has also a median inner hook 
a short distance below these lateral ones. The seventh spine is much curved and has 
only the inner basal upwardly directed median tooth which is also present on all the 
others (fig. 3). 
Locality. A single specimen from Minikoi, Prof. Stanley Gardiner’s Collection, no 
tube. It measures 20 mm. without its branchial crown and its greatest width is 2 mm. 
The gills, of which there are 20 pairs, are 3 mm. long and have large terminal filiform 
processes. The opercular pedicle is a little longer than the branchiz so that the operculum 
projects just above them. Owing to the condition of six of the spines this species might 
have been referred to the genus Hucarphus though it does not resemble any other species 
of this group so nearly as it does H. heteroceros. 
The setee are as usual in the genus—the uncini have seven teeth in the thorax and 
five in the abdomen, but are everywhere of the characteristic pattern. 
6. Hydroides monoceros, Gravier (21) 1908. 
Specific characteristics: opercular funnel asymmetrical and with about 16 serrations 
