iSqS- Platymaia, Alcock, Journ. Asiat. Soc. Bengal, vol. 64, pt 



2, p. 180. 

 1899. Platymaia, Alcock, Deep-sea Brachyura of RI.M.S.S. 

 Investigator, p. 45. 



Carapace suborbicnlar. Rostrum tridentate. No preocular 

 spine, but a post-ocular spine against which the eye is retractile, 

 but which affords no concealment to the eye. Eyes large, with 

 short eye-stalks. Epitome small, transverse. Basal antennal 

 joint short, cylindrical, free ; the flagellum and part of the 

 peduncle visible from above. Third maxillipeds with the fourth 

 joint narrow, and bearing the next joint at its summit- Chelipeds 

 in the adult male long, with a long inflated club-shaped palm; in 

 the female, short and slender. Ambulatory legs long, some of 

 them spiny, fingers of the hinder pairs compressed. Pleon in 

 both sexes wath all the segments separate. 



The above definition is borrowed from Alcock, with some 

 modifications to suit the new species here described. The account 

 of the chelipeds in the adult male still, however, rests only on 

 the type species, Platymaia wyvillcthomsoni, Miers, of which a 

 magnificent male specimen is figured by Alcock and Anderson, 

 in the Illustrations of the Zoology of the R.I.AI.S.S- Investigator, 

 Crustacea, pi. 16, 1896. In that species both sexes have the 

 •penultimate joint in the last three pairs of legs somewhat dilated] 

 and compressed, but there is no dilatation worthy o* remark in 

 the corresponding part of the new species. 



Platymaia tqrbynei, n. sp. 

 Plate 5. 



The type species of the genus was dredged by the "Challenger" 

 north of the Admiralty Islands, and by the " Investigator " in the 

 Andaman Sea. More recently the '" A^aklivia " procured it rather 

 plentifully at the Nicobar Islands (Chun, Aus den Tiefen des Welt- 

 meeres, pp- 396, 370, fig. in text). Accordingly, notwithstanding 

 the differences between the sexes and between the younger and 

 older stages pointed out by Major Alcock, the figures by several 

 mdependent observers show that its general configuration is fairly 

 constant. The new African species agrees \Nith it in too many 

 points to admit of generic separation, tJiough specifically it is very 

 obviously distinct. 



The distinguishing marks are the prolongation of the central 

 spine of the depressed and then upward turned rostrum much in 

 advance of the two lateral spines ; the shape of the carapace, 

 ^\ hich has the hind margin much more broadly rounded ; the pro- 

 portion of the ambulatory legs to one another, the proportions of 

 their joints, and the shape of the penultimate jioint in the hinder 

 limbs. 



B 2 



