137 



The genus Discoplax A. Milne-Edwards *) is very nearly allied to (if not identical with) 

 Cardisoma, but as de Man ') recently pointed out, it is wrong to follow Ortmann and Alcock 

 in simply uniting the only species D. longipes with C. hirtipes Dana, for there are nümerous 

 points of difference. 



For the present leaving aside this D' longipes, we admit but two species in the Indo- 

 Pacific region, where they represent the typical Atlantic genus Gecarcinus. 



Key to the species : 



Epibranchial tooth immediately behind external orbital angle ; lateral 

 margins of carapace strongly and abruptly bulging behind epibranchial 

 teeth; postfrontal lobes indistinct; regions scarcely indicated, hairy 

 part of pterygostomial regions as broad as base of buccal cavern ; 

 infra-orbital border passing rectangularly into the lateral one. Mero- 

 podites of walking legs with some few hairs only at hind margin . C. carnifex (Herbst) 



Epibranchial tooth at a longer distance behind external orbital angle ; 

 lateral margins of carapace less bulging behind epibranchial teeth ; post- 

 frontal lobes and regions of carapace much more distinct ; hairy part 

 of pterygostomial regions much broader than base of buccal cavern ; 

 infra-orbital border passing with an acute angle into the lateral one. 

 Meropodites of walking legs bordered with bristles at hind margin . C. hirtipes Dana :! ) 



i. Cardisoma carnifex (Herbst). 



Literature: ALCOCK. Journ. As. Soc. Bengal, v. 69, prt 2, 1900, p. 445—446. 



Stat. 213. Saleyer Island, south of Celebes, 1 rf (ad), 2 $, with eggs. 

 Stat. 279. Roma Island, north-east of Timor, 2 Q. 



This well-known species, like the preceding, occurs in the whole Indo-Pacihc region. 



Gecarcoidea H. Milne-Edwards. 



1837. Gecarcoidea H. Milne-Edwards. Hist. nat. Crust., t. 2, p. 25. 

 Literature: ORTMANN, Zool. Jahrb., Syst., Bd 7, 1894, p. 738. 



The rather insufficiënt diagnosis of H. Milne-Edwards, who in 1853 changed the name of 

 the genus into Pelocareiuns, induced Wood-Mason and afterwards de Man to suppose, that their 



1) Nouv. Arch. Mus. Paris, t. 9, 1873, p. 294, pi. 15. Hab. New Caledonia. 



2) Abh. Senckenb. Ges., Bd 25, Heft 3, 1902, p. 548—549. 



3) Literature: Alcock, Journ. As. Soc. Bengal, v. 69, prt 2, 1900, p. 447. Krom the synonymy here given Discoplax long 

 should be omitted, as has been mentioned. but two other names should be added : firstly C. frontalis II. Milne-Edwards from the Loyalty 

 Islands near New Caledonia (Ann. Sc. Nat. (3) t. 20, 1S53, p. 204, see de Man, Abh. Senckenb. Ges., Bd 25, Heft 3, 1902, p. 548, 

 pi. 20, f. 14), which most likely is at most a subspecies of C. hirtipes, and secondly C, obesum de Man (nee Dana) (Notes Leiden Mus., 

 v. 2, 1880, p. 35), which certainly belongs to this species. 



Miss RATHBUN (Buil. U.S. Fish Comm. for 1903, v. 23, prt 3, 1906, p. 838) has recently replaced the name hirtipes by 

 rotundum, identifying Dana's species with " Thelplutsa" rotunda Quoy et Gaimard (Freycinet's voy. around the world, t. 3, Zool., 1825, 

 p. 527, pi. 77, f. 1), but, as i'ilman (I'roc. Zool. Soc. London, 1909, p. 711) tightly remarks, description and Bgure of those earlier 

 French authors are equally poor and wholly insufficiënt to allow of an exact determination. 



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SIDOGA-EXPEDITIE XXXIX C. iS 



