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

 Cardisonia , but as de jNIan -) 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 numerous 

 points of difference. 



For the present leaving aside this /> longipes^ we admit but two species in the Indo- 

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



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. Cardisouia carnifex (Herbst). 



Literature: Alcock. Jouni. As. Soc. Bengal, v. 69, prt 3, 1900, p. 445—446. 



Stat. 213. Saleyer Island, south of Celebes, i cf (ad), 2 9. with eggs. 

 Stat. 279. Roma Island, north-cast of Timor, 2 9. 



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



Gecarcoidea H. Milne-Edwards. 



1S37. Gecarcoidea H. Milne-Edwards. Hist. nat. Crust., t. 2, p. 25. 

 Literature: Ortmann, Zool. Jahrb., Syst., Bd 7, 1S94, p. 738. 



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

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



1) Nouv. Arch. Mus. Paris, t. 9, 1873, P- ^94, pi. 15. Ilab. New Caledonia. 



2) Abh. Senckenb. Ges., Bd 25, Heft 3, 1902, p. 54S — 549. 



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

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

 Islands near New Caledonia (Ann. Sc. Nat. (3) t. 20, 1853, p. 204, see de3Ian, Aloh. 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. obesiim de Man (nee Dana) (Notes Leiden Mus., 

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



Miss Rathbun (Bull. U.S. Fish Comni. for 1903, v. 23, prt 3, 1906, p. 838) has recently repLaced the name hirtipes by 

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

 p. 527, pi. 77, f. I), but, as Cu.MAN (Proc. Zool. Soc. London, 1909, p. 711) lightly remarks, description and figure of those earlier 

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



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SIF.OGA-EXPEIIITIE XXXIX <\ l8 



