2 AET. 1. — CHARLES ELIOT: 



the commonest nudibranch in these waters, Cacllina, and Roslanga; 

 but Tritonia is absent and so are the Pseudodorididse (Acanthodo- 

 is, Adalaria, etc.) which are characteristic of the colder seas. 

 On the other hand the tropical element is very large and it is 

 remarkable to find equatorial forms such as Sphaerodoris, Cerato- 

 soma, Kalinga, Bomella and Pteraeolidia occurring so far north. 

 Phyllidia is represented in the collection but only by specimens 

 from the Bonin and Loochoo archipelagoes, which though Japanese 

 territory are considerably to the south of the larger islands. 



Though the collection consists chiefly of forms which are 

 found in the tropics, yet it is distinguished from the typical 

 equatorial fauna by the absence of several large and conspicuous 

 genera such as Hexabranchus, Asteronotus, Kentrodoris, Orodoris. 

 Also the species of Chromodoris (3) and Doridopsis (1) are rela- 

 tively neither numerous nor brilliantly coloured. 1} 



The Polyceridse (especially Plocamophems), Melibe, and Pleu- 

 rophyllidiidse are all remarkably numerous considering the size of 

 the collection. 



Though I have registered no less than nine new species, I 

 confess that I feel doubtful if they will prove valid in the light 

 of further research. In defence of them, it may be said that the 

 specimens examined by me do not correspond with any published 

 description. But these descriptions 2 ' are to a large extent based 

 on single preserved specimens and take no account of possible 

 variations. Thus, the animal here named Pleur ophyllidia japonica 

 is decidedly not PI. compta as defined by Bergh. It shows dif- 

 ferences in the side lamellae, head- shield and radula, all of which 

 organs are supposed to offer good specific characters. But when 

 one finds animals very like PL compta, coming from the same 

 waters but differing in the organs mentioned, one must allow for 

 the possibility that the species in this genus are more plastic 

 and variable than was supposed. Again, the animals belonging 



1) I should aid that though Doridopsis gemmicea is not in the present collection I have 

 found it in abundance at ilisaki. 



2) The moä!; important account of Japanese nudibranchs is contained in Bergh's two papers, 

 "Beiträge zur KenntnLss der jxpanischen Mudibranchien" in the "Verhandlungen der k. k. Zoolo- 

 gisch-botanischen Gesellschaft zu Wien," 1830 and 1881. 



