NOTES ON SOME BRITISH NUDIBRANCHS. 363 



The jaws bear two or tliree rows of denticles. The radula is triseriate, 

 and consists of twenty and fourteen rows respectively in the two speci- 

 mens. The central tooth (Fig. 15. a.) has a strong central cusp, which 

 bends slightly downwards, and hence sometimes appears asymmetrical 

 when pressed Hat in a slide. On each side of it are a number of small 

 denticles of varying shape and size. The smallest number observed 

 was sixteen and the largest twenty-four. The laterals (Fig. 15. b.) are 

 also broad, with slightly lower cusps, and twenty to thirty accessory 

 denticles on the inner side. No denticles were visible on the outer side 

 of the laterals. 



The penis, which is partially protruded in one specimen, is sickle- 

 shaped and very deeply grooved, consisting of a lamina folded down 

 the middle and probably capable of assuming a foliaceous expansion. 

 This part is unarmed, but the base of the penis and the end of the 

 spermatic duct bear numerous yellow cones (Fig. 16.) terminating in 

 a short bent appendage. They appear to be soft and not spiculous 

 or chitinous. The spermatotheca is large and spherical. 



As this species has smooth rhinophores and the radula of Goryphella, 

 I provisionally refer it to that genus in order to avoid multiplying 

 genera. But in many of its characters — such as the shortness of the 

 oral tentacles, the length of the cerata, the position of some of the 

 cerata in front of the rhinophores, and the conformation of the penis — 

 it differs markedly from the described Coryphellie, and it may ultimately 

 prove better to make it the type of a new genus. 



CRATENID^, BERGH. 



(Behgh, MaJ. Unt. in Semper's Reise7i, Heft i., 1870, pp. 1-4, and Heft 

 xviii. pp. 1021-4. Beaumont, "Fauna and Flora of Valentia Harbour," in 

 Proc. Royal Irish Acad., 1900, pp. 834-8. Fkiele, " Molhisken der ersten 

 Nordmeerfahrt," Bergen^s Museums Aarhoij, 1902, No. 3, p. 9.) 



As the autliors cited above ol)serve, Bergh's classification of this 

 group raises many difficulties in practice, on account of the minuteness 

 of the generic distinctions and the doubt whether the forms really 

 possess the characters which he attributes to them. He divides the sub- 

 family into five genera — Cuthona, GuthoneMa, Ci'atena, Jlervia, and 

 Phedilla. Of these the last named differs from the others in several 

 particulars. Hervia also may be set aside as characterized by the 

 corners of the foot being prolonged into tentacular processes. It is not 

 recorded from Ih'itish waters, though as the ha])itat of one species is the 

 Northern Atlantic it may some day be added to our fauna. The other 

 three genera, Cuthona, CuthoneU'a, and Gratena, are closely connected, 

 and to them must l)e added in my opinion Atuphorina. Bergh classes 



NPW SEJIIES. — VOL. VIJ. NO. 3. 2 A 



