OPISTHOBRANCHIATA FEOM THE ABROLHOS ISLANDS. 573 
and looked as if it were in the process of boring its way down to get into the 
body-cavity. This specimen was very noticeable from the outside, and its 
long lateral appendages and most of the body projected freely from the 
dorsal snface of its host. In examining this individual it was noticed that 
two peculiar sac-like structures containing eggs of a deep golden-yellow 
colour were projecting from the much dilated renal pore. Fui'ther exami- 
nation and dissection revealed the presence of a second and slightly larger 
example of the parasite completely hidden within the body of the host — the 
measurements of this specimen are given above. It was lying within the 
renal duct at its posterior end, but it was so large and its lateral arm-like 
appendages spread about so much among the viscera that it was not possible 
to see whether the animal was completely confined within the renal duct, 
which had become enormously dilated and ramified, or whether it had broken 
through the wall of this structure. 
While the specimen on the outside of the Nudibranch contained eggs 
within the body, visible through the semitransparent bod3'-wall as a tracery 
of lines, it showed no sign of egg-sacs. If these had not been torn off, there- 
fore, it would appear as if the production of eggs had not proceeded far in 
this individual. In the second specimen, on the other hand, egg-sacs were 
present and of large size. As noted above, the}' projected through the renal 
pore, which was much enlarged or perhaps actually broken, and also projected 
through the partiall}' closed branchial aperture. They were extremely thin- 
walled and delicate, and in the subsequent process of excavating the rami- 
fications of the parasite from the body of the host they were badly broken 
up — fortunately not until after they had been measured. When the branchise 
were expanded, the egg-sacs must have lain among the branchial plumes as 
described in S. gracilis. The body of this individual also contained a number 
of eggs showing through the body-wall, and arranged in a series of inter- 
lacing lines which passed out into the lateral pi-ocesses. 
No trace of a male individual was found either on or near the females, or 
upon or in the body of the host. This is rather remarkable in view of the 
fact that Hancock and Norman state that the males, sometimes to the number 
of a dozen, are generally to be found associated with the females. 
The present species is undoubtedly congeneric with S. gracilis Hancock 
and Norman, and quite similar to it in a number of ways. It differs in a 
number of points, however : the presence of the dorsal sacs, the segmentation 
of the abdomen, the more degenerate condition of the thoracic limbs, the 
greater length of the lateral appendages, and certain differences in the mouth- 
parts inter alia, and so it is here listed as a new species under the name 
Splanclmotrophus sacculatiis. It is interesting to find a form from the 
Antipodes so closely allied to S. gracilis, heretofore only recorded from 
the European seas. 
