340 NOTES ON SOME liKITLSH NUDIBRANCHS. 



In 1862 Alder and Hancock described (I.e.) a new British Dorid, 

 which they identified with the D. testudinaria of Kisso. From some 

 unpublished notes preserved in the Hancock Museum at Newcastle-on- 

 Tyne, it is probable that they based this identification, not on Kisso's 

 description, but on specimens sent from the Mediterranean and labelled 

 D. testudinaria, which they considered identical with their specimen 

 from Herm Island.* Kisso's description is vague, inadequate, and, as 

 pointed out first by Philippi (Enum. Moll. Sicil., vol. ii. p. 78), probably 

 inaccurate. Bergh and others have thought that it refers to Platydoris 

 argo. But since Alder and Hancock have given the name to a fully 

 described animal, which is possil)ly identical with Kisso's animal, it 

 would seem that their interpretation of the name must be regarded as 

 authoritative. After Alder and Hancock had assigned the name 

 D. testudinaria to an identifiable form, von Jhering; gave the name 

 Archidoris stellifera to Mediterranean specimens, which seem to me to 

 belong to the same species. His description appears to have been only 

 in MS., and publication dates from the memoires of Vayssiere, who uses 

 the same name. As will be seen from the notes here given, stellate 

 forms are found on the Britisli coast, and appear to be specifically the 

 same as the less ornate variety described by Alder and Hancock. It is 

 remarkable, however, that Vayssiere states that the mouth of his 

 specimens is armed with a chitinous ring. I could not discover this 

 structure in the specimen which he kindly sent to me. 



Alder and Hancock, in the Ann. and Mag. of Nat. Hid., I.e., expressed 



the opinion that 1). testudinaria and D. planata. are distinct though 



similar species. Subsequently Alder in Jeffrey's Conclwlogy (I.e.) came 



round to the opposite view, and staled tliat an examination of further 



specimens of difFerent sizes from the Clyde proved that D. jyloiata is 



the young of I), testudinaria. It is extremely dillicult to form any 



decided opinion on this question. The external characters are likely to 



vary considerably at different periods of the animal's growth, and it 



would appear that in D. testudinaria {stellifera) a labial armature may 



or may not be developed. Vayssiere reports its presence, and Alder 



and Hancock (Ann. and Mag. N. II., I.e.) say of D. testudinaria and 



D. 2)lanata, " the character of the tongue is similar in each." On the 



other hand, in a numl)cr of specimens from I'lymouth which I have 



examined, I have found a decided labial armature in the small flat 



individuals and none at all in the large plump ones. It is present in 



the specimen of D. i)lanata from Alder and Hancock's collection at 



Newciistle. On the whole I am inclined to think that there are two 



separate forms which are very much alike in their younger stages. 



• It is even possible tliat A. & H. may have obtained the specimens from Risso, or from 

 some one who knew the animal which he called D. testudinaria. They were writing about 

 Nudibranchs in 1841, but probably began collecting earlier. 



