SOME NUDIBRANCHS 105 



SOME NUDIBRANCHS, INCLUDING HERMsEA 

 DENDRITICA, AND LAMELLIDORIS ASPERA, 

 FROM THE FORTH AREA. 



By William Evans, F.R.S.E., and Lieut. W. Edgar Evans, B.Sc. 



As on land, so in the sea, there occur molluscs having shells 

 and those without them ; that is, snails and slugs. The 

 scientific name for the sea-slugs is Nudibranchiata or, as 

 some prefer it, Nudibranchia. For delicacy of form and 

 colour, the group can lay claim to some of the most beautiful 

 of nature's productions. Sixty to seventy years ago the 

 British species were investigated by Alder and Hancock, 

 whose exquisite coloured drawings, illustrating their famous 

 1 Monograph," x have ever since been the delight of marine 

 zoologists. 



Many of Alder and Hancock's specimens were obtained 

 on the north-east coast of England, and thus at no great 

 distance from where the coast-line of the Forth area begins 

 in the south. According to the recent supplement to the 

 " Monograph" there are 125 species, or thereby, now known 

 from British waters. Of these only some twenty-nine or 

 thirty at most equal to no more than half the Clyde list 

 have been recorded from the Firth of Forth, 2 a number which 

 doubtless falls considerably short of the actual Nudibranch 

 fauna of the area. In the present paper we record two 

 additions to the list, namely, Hermcea dendritica, A. and H., 

 and Lamellidoris aspera, A. and H., both recently obtained 

 in the course of some promiscuous shore-collecting a clear 

 indication of what a systematic search for this group of 

 molluscs might be expected to yield. 



During the spring of 191 5 a small sea-water aquarium 

 was fitted up by one of the writers (W. E. E.), in our house 



1 " Monograph of the British Nudibranchiate Mollusca," Ray 

 Society, 1845-1855 ; Supplement by Sir C. Eliot, 1910. 



2 For references to literature, see paper by W. E. in Proc. Roy. Phys. 

 Soc. Edin., xvii., pp. yj and 38. 



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