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distinctly visible, forming with the edge of the epistome on either side a 

 subtubular exhalant opening when the external maxillipeds are shut. But a 

 condition closely approaching this is to be found in several species of Paratel- 



phusa. 



The mandibular palp is exactly like that of Paratelphusa, and consists of 

 two joints (the normal 1st and 2nd joints being indistinguishably fused), of 

 which the terminal one is split into two lobes— a broader anterior, and a 

 narrower posterior — which embrace the incisor process of the mandible. 



The only two points that seem constantly to differentiate Gecardnucus 

 from Paratelphusa are the following : — 



(1) The front is a long, narrow, greatly deflexed lobe, hardly wider than 

 the orbit in the adult. There are several species of Paratelphusa in which, in 

 old individuals, the front becomes relatively narrow, but there is none that I 

 know of in which it is not much wider than the orbit ; 



(2) The dactyU of the crawling legs are decidedly slender. 



A third difference that only, so far as I know, holds good for Gecarcinums 

 jacquemontii, is that the abdomen of the adult female is narrow and has a 

 terminal joint the length of which equals, or sHghtly exceeds, its proximal 

 breadth. 



It seems permissible to split the genus into two sections as follows : — 



I. Orbits of the usual pattern ; a small lateral epibranchial tooth or 

 tubercle .....••• Ct/lindrotelphtsa, 



II. Lower outer corner of orbit drawn out as a distinct gutter-like 



recess ; no trace of a lateral epibranchial denticle . . . Gecardnucus. 



The genus Gecardnucus, in the wider sense, is found on the south Indian 

 plateau and in New Guinea. The species from New Guinea should, I think, 

 be placed in the subgenus Cylindrotelphiisa. 



Subgenus I. — Gecarcinucus. 



Carapace very broad. Orbits hardly visible in a dorsal view, and contorted, 

 their loiver outer corner being produced into an outlying bay ; external orbital 

 angle suppressed. 



Edge of cxntero-lateral borders of carapace smooth or feebly crenulate ; no 

 trace of a lateral epibranchial tooth. 



Abdomen of adult female narrow, the 7th joint being of an elongate 

 triangular form. Seventh segment of abdomen of adult male elongate, tongue- 

 shaped. 



Excurrent branchial openings distinctly subtubular between the edge of 

 the external maxillipeds and the epistome when the maxillipeds are shut. 



Teeth of the distal part of the chelaj small translucent, in a very close-set 

 regular row. 



