OPISTHOBRANCHIATA KEOM THE ABROLHOS ISLANDS. 569 
7.1.1.1.7 {i.e., 17) and in the newer portions S .1 .1 .1 .8 (i.e., 19). The 
rachidiai tooth is in the form of a broad irregular octagon with its posterior 
side uncnrved and thicker in its anterior half. Its front edge is straight, 
but furnished with four curious papilliform denticles directed backwards — 
one of the inner o£. these bifid. In the radula of the specimen examined 
it was al\va3rs the inner one on the same side. The first lateral has an 
irregular elongated base lying at an angle of about 40° to the middle line 
of the radula. It bears two very strong, backwardly directed, conical 
spines — one at its anterior end and the other about two-thirds of the way 
back. Tliis is followed by a series of teeth, seven or eight in number. They 
take the form of approximately square plates in the inner teeth, but become 
oblong and less strong towards the outside. 
Labial Armature. The lips are furnished with a lining of thin chitin, which 
has an oval opening, whose long axis is vertical. 
The anus lies on a short rounded papilla in the middle line behind the 
junction of the bases of the posterior branchial plumes. 
The genital aperture lies near the anterior end in the light space between 
the two lateral dark bands and about halfway between the head and the 
branchipe. 
JSotes. The species is represented by one specimen, which was taken on the 
Abrolhos, but with no details of the exact locality. 
In spite of the presence of a labial cuticle rather more strongly developed 
than in other forms, there is no doubt that this belongs to the genus 
Nemhrotha. It does not appear to agree with any previously described. 
A CoPEPOD Parasitic on Gbbatosoma bbevicavdatum. 
The presence of CJopepoda parasitic upon Nudibranchs has been reported 
by several authorities. The first record is apparently that of Ley dig (56), in 
1853, who constituted the genus Dor'ulicola for Copepods found on Dorids. 
Similar forms are also reported by Alder and Hancock (5) from Archidoris 
tuberc.ulata and Antiopa cristata, and they were referred to the genus 
Ergasilus, although they were probably congeneric, if not even conspecific, 
with Ley dig's forms, as was pointed out later by Hancock and Norman (47). 
They are not highly modified animals and apparently more in the nature 
of epizoitic forms, and their parasitism has not been proved. 
In addition to these, however, a group of highly specialised forms, 
undoubtedly parasitic, have also been described. The first, reported by 
Hancock and Norman (47), are : — Sjjlanclmotro'plms gracilis, parasitic on 
Acanthodoris pilosa and Idalia aspersa from the English coast, and <S'. hrevipes, 
parasitic onDoto coronata and Corypliella rujih^xinchialis also from the English 
coast. The only other authority that has dealt with these parasites is 
R. Bergh, who has recorded the following : — 
