CKUSTACEA OF THE MERGrtJI ARCHIPELAGO. 137 



DiosiPPE *, nov. gen. 



Cleistostoma, de Haan, partim. 



The genus Gleistostoma was founded by de Haan upon two 

 Japanese species — C. dilatata and G. pusilla. An examination 

 o£ a large number of specimens of the latter species which I 

 found in a small collection of Japanese Crustacea, kindly pre- 

 sented to me by Dr. Anderson, now makes it very probable that 

 the two species of Cleistostoma described in the ' Fauna Japo- 

 nica ' are not so closely allied to one another as de Haan sup- 

 posed, and that they are even generically distinct. De Haan 

 had only young male specimens of C. pusilla at his disposal, 

 whereas my specimens are of a larger size, and there are both 

 males and females among them ; so that I have been enabled 

 to observe some characters that were overlooked by de Haan. 

 I find that the merus-joint of the external maxillipeds of O. 

 pusilla has not the same quadrate form of the ischium-joint, but 

 that the outer foot-jaws of this species resemble much more 

 those of some Dotill(S. The external maxillipeds of Cleistostoma 

 dilatata, figured by de Haan, on the contrary, have a different 

 form, their merus-joint being as quadrate as the ischium-joiat. 

 Moreover, the meropodites of the ambulatory legs of G. pusilla 

 present traces of the remarkable "tympana" which are so cha- 

 racteristic of the true Dotillae and Scopimerce; though small, they 

 are quite distinct on the outer surface of the meropodites of the 

 last pair of legs in the male. These " tympana " were over- 

 looked by de Haan, who had only small specimens at his dis- 

 posal, as I have already observed. Furthermore, the whole outer 

 appearance of Cleistostoma dilatata is quite difi'erent from that of 

 C. pusilla,th.e lateral margins of the cephalothorax of the former 

 species presenting none of the small emargination immediately 

 behind the external orbital angles which characterizes C. pusilla, 

 and is also observed in many species of Dotilla, and the front 

 is much broader in G. dilatata than in the other species. 



The Mergui collection contains an interesting new species, 

 which agrees in many essential characters with Gleistostoma 

 pusilla, though specifically distinct. I propose, therefore, for 

 these two species the new genus Dioccippe, which may be dis- 

 tinguished from the genera Dotilla and Scopionera chiefly by 



* Vioxippe, one of the Heliads, 



