158 



Miss. Rathbun ^), hovvever, maintains Heieroplax as a distinct oenus and records both of 

 Stimpson's species from the Gulf of Siam, but without any comment whatever. 



As to Platyozhis it was first established b}- Borradaile as a subgenus of Psejidoziiis\ 

 afterwards -) it was declared to be nearer related to Piliivnioplax\ but still regarded as belonging 

 to the Xanthidae. Though it must be admitted that the hmit between Goneplacidae and Xanthidae 

 is largely arbitrary, the position of the male organs in such genera as Piluiiuioplax, Eiicraic 

 etc. certainly points to the Goneplacidae, and I have associated Platyozuts with Eiicrafe, on 

 account of its general appearance, notwithstanding Borradaile's not mentioning anvthing about 

 the antennae. 



Five species in all are here included in the genus ^), one of which has been dredged 

 by the "Siboga". 



Key to the species : 



1. Margins of carapace without teeth or at most with two incon- 



spicuous nodules. Chelipeds in cf very massive, longer than 



the walking legs E. ham il toni Mc Culloch*j 



Antero-lateral margins of carapace four-toothed 2 



2. Front transversely grooved. Antero-lateral teeth of carapace all 



distinct, but the two middle ones on each side the largest . 3 

 Second and fourth antero-lateral teeth nearly obsolete ... 4 



3. Large species (breadth of carapace 30 — 40 mm.); carapace 



much convex longitudinally, not sculptured , only with an 



oblique ridge on posterior teeth E. crcnata (de Haan) °) 



Small species (breadth of carapace 15 — 20 mm.); carapace more 

 flattened, with some short transverse ridges anteriorly; on the 

 branchial regions at each side a more or less distinct, longi- 

 tudinal ridge, laterally of which the carapace is strongly 

 declivous E. sii/catifrons (Stimpson) 



4. Length of carapace to breadth as i : 1.27 E. daitata (Stimpson)") 



Length of carapace to breadth as i : 1.46 E. transversa (Stimpson) '^) 



I. Eucratc sidcaiifrons (Stimpson). 



1858. FiliDunoplax siilcatifrons Stimpson. Proc. Ac. Nat. Sc. Philadelphia, 185S, p. 93. 

 1877. Pilutnnoplax siiicatifrons Targioni-Tozzetti. Viag. "Magenta", Crost., p. 102, pi. 7, f. 2. 



1) K. Dansk. Vid. Selsk. Ski., 7. Raekke, Afd. 5, n" 4, 1910, p. 342. 



2) L. c, p. 429. 



3) The species E. scxdentala Haswell, mentiond by Alcock (1. c, p. 301J, in lealily belongs to tlie Pi io/wJ)/aiinac 

 {Homoioflax Rathbun). 



4) Ree. Austial. Mus., v. 7, 1908, p. 58, pi. 12, f. i. Hab. Queensland. 



5) Camcr (EucratcJ crenattts de Haan, Faun. Japon., Crust., 1835, p. 51, pi. 15, f. I ; Eiiciaic crcnata Uiimann, Zool. Jahib., 

 Syst., Bd 7, 1894, p. 688; Rathbun, Proc. U.S. Nat. Mus., v. 26, 1903, p. 23. Hab. Japan. 



6) Heieroplax dcntata Stimpson, Proc. Ac. Nat. Sc. Philadelphia, 1858, p. 94; K.vrHliUN, K. Dansk. Vid. Selsk. Skr., 7. Raekke, 

 Afd. 5, n» 4, 1910, p. 342; Stimpson, Smithson. Inst., Miscell. CoU., v. 49, 1907, p. 94. Hab. Hongkong and Gulf of Siam. 



7) Heieroplax transversa Stimpson, Proc. Ac. Nat. Sc. Philadelphia, 1858, p. 94; Rathbun, K. Dansk. Vid. Selsk. Skr., 7. 

 Kaekke, Afd. 5, n» 4, 1910, p. 342; Stimpson, Smithson. Inst., Miscell. Coll., v. 49, 1907, p. 95. Hab. Hongkong and Gulf of Siam. 



