l82 



legs with a subdistal spine at the ^interior margin, save in the 



case of the last legs G. sinuatifrons m^r^ 



Antero-lateral margins of carapace with an epibranchial tooth, 



behind external orbital angle 2 



2. Lateral margins of carapace feebly convergent backward; external 



orbital angle spiniform ; eye-stalks reniform, greatly widening 



distally. Meropodites of walking legs with a subdistal spine at 



anterior margin G- renoculis Rathbun ') 



Lateral margins of carapace distinctly convergent backward ; exter- 

 nal orbital angle obtuse or subrectangular ; eye-stalks club-like. 



Meropodites of walking legs unarmed, last pair of legs with the 



propodites broadened and transformed into swimming paddles . G. maldivensis Rathbun 



I. Goneplax sinuatifrons Miers. PI. 9, Fig. 2a. 



1886. Gonoplax sinuatifrons Miers. Rep. "Challenger", Brachyura, p. 246, pi. 20, f. 2. 



Stat. 181. Amboyna. Depth 36—54 m. i cf. i 9> 8 juv. (aet. div.). 



MiERS rightly remarked that this species is extremely like the European G. rhomboidc. 

 (Fabricius), which must be regarded as hardly a subspecies of G. angulata, but it differs in having 

 the anterior margin of the front not straight, but slightly concave; it must be said, however, that 

 also in the European species the same character, though less marked, is to be observed. The 

 shape of the carapace is nearly exactly the same, but the slight prominence or tubercle, 

 representing an obsolete epibranchial tooth, in G. rhoiuboides is wholly wanting in the Iiidian 

 species, and the chelipeds are short and not greatly elongate in the cf of the latter species, 

 but this may be perhaps attributed to the small size of the examples as yet found. There is, 

 however, another and perhaps more remarkable feature in the Indian species, viz. the breadth 

 of the abdomen of the cf, which seems to have been overlooked by Miers, for he expressly 

 states that in all species of Goneplax the abdomen entirely covers up the space between the 

 bases of the last legs. Now, in the present species, the first segment is hidden under the 

 carapace, the second segment is exactly one-half, and the third segment not completely two- 

 thirds of the breadth of the last segment of the sternum (fig. 2«), so that the lateral 

 parts of the third segment of the abdomen conspicuously fall short of the 

 coxopodites of the legs"). In G. rhomboides^ on the other hand, the first segment is 

 exposed, as broad as the next, both not covering up the last segment of the sternum, the third 

 segment of the abdomen nearly touches the coxopodites of the last legs. In both species the 

 remaining parts of the abdomen are only very slightly narrowed towards the tip, but in G. 

 sinuatifrons the terminal segment is shortly-triangular, twice (in the 9 even 3 times) as broad 

 as long, in G. rhomboides, however, more elongate and longer than broad. 



1) Proc. U.S. Nat. Mus., v. 48, 1914, p. 145. Hab. Philippines. 



2) It may be added, that the same is the case in the $, in which the alidomen is only slightly broader than in the rf ; only 

 the first segment is not concealed beneath the carapace. 



34 



