1908.] RIVER-CRAB FROM NEW GUINEA. 961 



slight ridge lams backwards from it along the antero-lateral 

 margin, interrupted by the cervical groove and then foi-ming a 

 small epibranchial tooth ; almost immediately Ijehind this the 

 ridge runs on to the dorsal surface of the branchial I'egion and 

 dies away at about the anterior third of the length of the carapace. 



The lower margin of the orbit is concave as seen from below ; 

 it has no tooth at its inner angle, which is indistinctly separated 

 from the inner suborbital lobe. On the lower surface of the 

 carapace the pterygostomial groove is well-marked and a faint 

 continuation of the cervical groove separates the sub-hepatic and 

 sub-branchial regions. 



The epistome has the middle lobe more rounded than in G. jac- 

 •quemontii and the lateral portions less concave but more pro- 

 minent anteriorly. The lobe of the first maxillipeds forming the 

 floor of the bi-anchial channel is considerably more exposed than 

 in that species. The third maxillipeds have the ischium strongly 

 grooved along its whole length, the merus broader than long, its 

 anterior edge oblique and slightly concave ; the exopodite extends 

 a little way beyond the ischium. 



Chelipeds veiy unequal, the larger one very massive in the 

 male. Merus long, nearly the whole of it visible from above 

 beyond the carapace, each of its three edges carrying a row of 

 sharp spiniform teeth. Carpus with a strong spiniform tooth on 

 the inner side, behind which the inner edge has, at most, one or 

 two minute granules ; the lower double tooth, present in G. jac- 

 quemontii, is here wanting. Chelfe smooth, with some faint 

 rugosities on the outer surface ; the upper and lower mai'gins are 

 rounded and there is a single blunt tooth at the ^^roximal end of 

 the lower edge. The palm of the lai^ger chela is but little longer 

 than high ; between the bases of the fingers on the outer side is 

 a large rounded or subconical tubercle. The fingers are strongly 

 compressed and deep, equal to or shorter than the palm ; there is 

 one large serrated tooth on the immovable finger and two, smaller, 

 on the dactylus. The jDalm of the smaller chela is much longer 

 than, high, the tubercle on the outer side is small, the fingers are 

 more slender and their teeth ax-e less prominent. 



The w'alking-legs are very long and slender, the second pair the 

 longest. The merus has a small subterminal tooth above ; the 

 pi'opodus has a few spines on its lower, and some, more minute, on 

 its upper edge ; the dactylus has four rows of spines. 



The abdomen of the male differs greatly from that of G. jac- 

 quemontii; it is strongly constricted a little way from the base 

 the narrowest part being at the junction of the fifth and sixth 

 somites ; the sixth somite is widened distally and the telson is 

 linguiform. The anterior part of the thoracic sternal surface of 

 the male is not setose as it is in G. jacquemontii. 



Locality. " Madeu, St. Joseph River, British New Guinea, 

 2000-3000 feet, W. Stalker coll." Mr. Stalker informs me that 

 the species probably burrows in swampy ground, although he did 

 not actually see specimens taken from the burrows. 



61* 



