i895- Platyviaia, Alcock. Jo"i"n. Asiat. Soc. Bengal, vol. 64, pt 



2, p. 180. 

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



Investigator, p. 45. 

 Carapace suborbicular. 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. Amindatory legs long, some of 

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

 both sexes with 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 cheHpeds in the adult male still, however, rests only on 

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

 magnificent male specimen is figured by Alcock and Anderson, 

 in the Illustrations of the Zoology of the R.I.M.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 turbynei, n. sp. 

 Plate 5. 



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

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

 Andaman Sea. More recently the " \aldivia " procured it rather 

 plentifully at the Xicobar 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 with it in too man}- 

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

 obviously distinct. 



The distinguishing marks are the prolongation of the ccnt'/al 

 spine of the depressed and then upward turned rostrum much in 

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

 which 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 



