28 NEMERTINES OF PLYMOUTH SOUND. 
positions on each side of the snout, and were about four times as large 
as the rest. Of the remainder two were placed on the left side and 
four on the right, but there was no kind of regularity in their 
arrangement. 
Joubin’s figure (Pl. XXX, fig. 3) shows well the peculiar posterior 
end so characteristic of this species. The nervous system is con- 
spicuously red. 
32. C. pAnrHERINUS, Hubrecht. 
C. MARGINATUS (pars), Joubin. 
I assign to this species a Cerebratulus dredged off Stoke Point on 
September 4th. 
In colour it agreed with the last species, from which it differed in 
the shape of the head, the absence of eyes, and in the posterior 
termination of the body. The anterior end was much swollen, and 
waves of contraction continually passed along the whole length of 
the animal. When it reached me it was extremely sluggish, 
exhibiting no other sign of life than these contractions. The snout 
was very pointed, and the cephalic slits were deep with closely 
opposed lips. Posteriorly the lips were opened, exhibiting deep pits 
leading to the side organs. At this point the slits were red. The 
animal, which was 4 cm. in length, was a ripe male. ‘The testes 
were present in a series from the blunt tail to the anterior fifth of 
the body. The mouth was a large corrugated slit just behind the 
cephalic slits. ‘The brain, which was situated just in front of the 
region where the cephalic slits widen out, showed through the 
ventral wall of the body and through the slits, laterally, as a bright 
red body. 
Joubin regards this species as a variety of C. marginatus, but 
Birger, who has obtained many specimens of both, is convinced of 
its validity, stating that all the forms which are pigmented in the 
manner characteristic of this species differ from 0. marginatus in the 
structure of the brain, 
IT am not sure whether this species is included by McIntosh as a 
variety of CO. angulatus. If not, this is its first record in Great 
Britain. 
This is another of the deep water species, which are, no doubt, 
more common than they seem, but which are at present nearly 
inaccessible to us. 
