173 



Report on the Nudibranchiate MoUusca of Plymouth 



Sound. 



By 

 Walter Garstaiig, B.A., 



Jesus College, Oxford; Assistant to the Director M.B.A. 



The species included in the present report have all, with one ex- 

 ception, been taken since the opening of the Laboratory in June, 1888. 

 Twenty-four genera and thirty-six species will be found recorded, 

 and these afford a considerable addition to the previously known 

 Nudibranchiate Fauna of the Sound. "^ Many of the specimens have 

 been obtained north of the breakwater by personally searching under 

 the stones and examining the rock-pools between tide-marks, but the 

 majority have been procured by means of the dredge, the best 

 grounds for this being near the Duke Rock Buoy and around the 

 Mewstone, a fine conical rock which marks the entrance to the 

 Sound on the east. 



That the Fauna of the Sound has deteriorated during the last 

 fifteen or twenty years seems undoubted, the cause being the con- 

 tinued increase in the amount of outfall of waste and commercial pro- 

 ducts from the Three Towns. t Vayssiere in his account of the 

 Opisthobranchiate Mollusca of the Grulf of Marseilles reports similar 

 impoverishment of the Fauna due to similar causes. At a part of 

 the coast, he says (25, p. 7), where Haminea cornea, Philine aperta, 

 Aplysia punctata, Doris virescens, Polycera quadrilineata, and 

 numerous Eolids used to be found in abundance, '' dans ces deux 

 dernieres annees il nous a ete impossible de rencontrer plusieurs de 

 ces mollusques et ceux qui ont resiste deviennent rares."J From 

 what I have heard of the zoological condition of other bays along the 

 Devon and Cornish coasts, I have no doubt that, especially among 

 the Nudibranchiata, there are many species to be found in the neigh- 

 bourhood which have not been taken by us inside the Sound or in 

 the adjacent waters. 



Notwithstanding this, some very valuable captures have been 

 made, notably two examples of Idalia aspersa and three specimens of 

 Lomanotus. The latter especially have proved of great interest, 

 and their characters afford a very valuable addition to our knowledge 

 of the genus in British seas. One species of Eolis appears to be 

 new. Moreover, I have throughout tried to make this report not 

 merely a list of species, but as far as possible a contribution to 



* Cf. this Journal, No. II, First Series, p. 185. 



t See the Director's Report, this Journal, New Series, No. I, p. 5. 



I Cf, also some remarks by Thompson of Weymouth (24). 



