20 NEMERTINES OF PLYMOUTH SOUND. 
variety of which species I was at first inclined to regard them. I 
am induced to separate them, however, because of the absence of the 
peculiar marking which is so characteristic of that species. 
The length is about 1 em, The head, which is very distinct from 
the body, is very broad at the level of the entrance to the side 
organs, and in shape resembles that of J’. melanocephalum. The 
anterior eyes are at least twice as large as the posterior. All four 
are of a brown colour, of irregular shape and not well defined. The 
ground colour is a pale yellow. On the dorsal surface there is a 
considerable development of reddish-brown pigment, which covers 
the whole of this surface of the body from just behind the posterior 
grooves to the tail. 
The proboscis stylet handle is of the shape described by McIntosh 
as characteristic of 7. Robertiane. 
I also refer here a specimen which I found the same month, which 
exhibited some differences from those above described. The length 
was 15 mm., the colour a uniform pale yellow. The general shape and 
the relation of head and body was the same as in the type form. 
The eyes were black and fairly distinct, the anterior being nearly 
twice the size of the posterior. The stylet handle resembled that of 
T. vermiculatum rather than that of 7’. Robertiane. 
All these specimens had ripe generative organs. 
Genus PROSORHOCHMUS, Keferstein. 
McIntosh characterises this genus as follows :—‘‘ Eyes four, not 
forming a rectangle ; snout dimpled, and furnished with a transverse 
superior lobe. Ovo-viviparous.” Of these three characters the first 
is scarcely available, as there is a general tendency towards this con- 
dition in the genus Jetrastemma, a tendency so great that in almost 
every species there are many individuals with the posterior eyes 
closer together than the anterior. McIntosh himself is not inclined 
to attach much value to the third character, as he says ‘it is a con- 
dition which further investigation will probably extend to many 
genera.’ The only character which is left is the second, and it 
appears to me questionable whether, on account of such a feature, a 
single species in all other respects Tetrastemma-like should be raised 
to the rank of a separate genus. 
19, Prosorwocumus Ciaparupil, Keferstein. 
Several specimens have been dredged, some from the Millbay 
Channel, others from the Duke Rock. None of these specimens 
