Cymonoinusy/-o?« the AmlnaaH Scd. 5G9 



are about once and a half, tlie I'oiirtli pair about once and a 

 quarter, the leugtli of tlie carapaee, tlic dactyl us iu I)oth 

 haviug the form of a small claw. 



Tlie length of the carapace is 8"5 millim., the breadth 

 posteriorly 8 n)illim., and the breadth across the antero- 

 lateral angles 7 millim. 



A single specimen was taken just inside the Andaman 

 basin, at 'Investigator' Station 322: lat. 11'' 26' 3'J", long. 

 i)2^ 53' 45", depth 378 fathoms ; bottom green mud with 

 Foraminifera. Unfortunately the bottom-temperature was 

 not recorded, but from previous observations we can infer 

 that it was between 47° and 48° Fahr. 



The chief dift\ rences between C andamanicus on the one 

 hand and the Atlantic species C. (jranulatus and C. quadratas 

 on the other are as follows : — 



The carapace is less square, its lateral borders being dis- 

 tinctly, if slightly, convergent anteriorly ; its cervical and 

 branchial grooves are somewhat fainter dorsally ; and 

 there are no spines at its antero-lateral angles. The rostrum 

 also is broader and much less prominent. 



The eye-stalks are quite immovaljle, and, though micro- 

 scopically grannlose, are not at all spinous. 



The cutting-edges of the fingers of the chelipeds are not 

 serrated, but, to the naked eye, are quite entire. 



From C. granulatus the present species is further dis- 

 tinguished by the much smaller subantennal tooth at the 

 outer angle of the buccal cavern ; and from C. quadratas by 

 the fact that the outer border of the antepenultimate joint 

 of the autennal peduncle is noi sharply serrated. 



3. Geographical Distribution of Ctmonomus and 



OTHKR DORIPPOID GeXERA. 



The singular sort of residual distribution of Cymonomus 

 requires to be explained, but as it fairly well exemplifies 

 that of the family, it may be considered with that of all the 

 other genera of the group, in the way that the subject has 

 already been presented by Professor Bouvierj in his paper 

 on the classification, origin, and distribution of the family, 

 published in the ' Bulletin de la Societe Philoraathique de 

 Paris ' for 1896-1897, pp. 67-69. 



1. DoRiPPE, Fabr. — This genus, which is composed of 12 

 or 13 recent species, belongs to the fauna of the shallow 

 water, not having hitlierto been found outside the 60-fathom 

 line. Its headquarters appear to be in South-eastern and 



Ann. & ^faJ. X. IlisL tSei-. 7. Vol. xv. 38 



