ro2 The Irish Nahiralut, May, 



111 his description of the species v. Graff seems to have been 

 doubtful as to the position of S. oiiiscoides Johnst. He says 

 " Not quite so sure is the identification with Sp. oniscoides 

 Johnston, and it is very possible that still a second species of 

 Spinther with parapodial cirri exists." 



Meanwhile no undoubted specimen of Johnston's species 

 had again been found in British waters, nor had any speci- 

 mens of the genus been found off Ireland. A few 3'ears ago, 

 however, in the course of the investigation of the fauna of 

 Larne lyougli by the Ulster Fisheries and Biology Association, 

 specimens of Spinther were found ; specimens have also been 

 taken in Belfast lyough, at the very spot mentioned by 

 Thompson (Nat. Hist, of Ireland) as the original locality . 

 These specimens were originally recorded by Prof. Gregg 

 Wilson (12) as ^. miiiiacais. On further examination he came 

 to the conclusion that they did not agree with v. Graff's 

 description of that species, and he therefore asked me to 

 determine the identification. I hope to prove in this paper 

 that these specimens belong to Johnston's kS. oniscoides^ and 

 that the species which v. Graff has described as .S. oniscoides 

 is not Johnston's species. 



The genus Spinther may be briefly defined as follows : — 

 Polychaeta, body oval in outline, convex dorsally, flattened 

 ventrally. Each ])ody-segment with a pair of hook bearing 

 parapodia laterall}^ and a pair of setiferous lamellae dorsally. 



On the head-region a single dorsal tentacle, with four eyes 

 at its base. Mouth ventral. Mid-gut with paired lateral 

 diverticula. A dorsal caecum is present. Branchiae absent. 

 All parasitic on marine sponges. 



The character which distinguishes ►S. viiniaceus and 6*. 

 archciis from Johnston's species, is the absence of a parapodial 

 cirrus. Now if it can be shown that there are two species of 

 Spinther with parapodial cirri, then it seems to me that the 

 species which comes from the place where Johnston's example 

 was found, and which more nearly answers io Johnston's 

 description, is the species which is entitled to be called kS". 

 oniscoides. I shall now describe the features in which my 

 specimens, from L,arne I^ough and Belfast Lough, differ from 

 V. Graff's 5*. oniscoides and from 5^. viiniaceus and S. arciicus. 



