2 I 7 



also as broad as the merus, but the antero-external angle of the merus is rounded off and 

 the same is expressly stated by Alcock. In the new species (fig. i a) the ischium is decidedly 

 broader than the merus, granulate, as also is the exognath, and the anterior and external 

 angle of the merus form a continuous arched line. 



6" Alcock states that the wrist of the chelipeds of X. moebii is acuminate at inner angle; 

 in the Leiden Museum specimen this angle is pronounced, not decidedly prominent. In 

 A', do lie hop ha/ he s this inner angle, though its exact shape is not easily to be made out, on 

 account of the numerous feathered hairs inserted here, is distinctly spiniform, more so than 

 in the other species. In Richters' species the chelae are unequal and the outer surface is 

 smooth and polished (Alcock) ; in the new species the hands are equal and the outer 

 surface is to a greater or lesser extent pubescent and granulate. 



•j" Finally, the most remarkable are the much elongated first abdominal appendages of the 

 cT of the new species. In adult and half- grown individuals these appendages 

 reach rather far beyond the terminal segment of the abdomen (fig. id), 

 even to the posterior margin of the buccal cavity; in very young specimens 

 (length of carapace about 2.5 mm.) they are entirely concealed beneath the abdomen. Neither 

 Richters nor Alcock have noted anything of this kind in X. moedn," and it is likewise not 

 to be observed in de Man's specimen. It is this character, together with the apparently 

 different development of the eye and the shape of the merus of the external maxillipeds, 

 which induced me to establish a new species for the "Siboga" specimens, the most conspicuous 

 feature of which is expressed by the specific name. 

 Dimensions in mm. : 



Fronto-orbital breadth. . ... 3.2 



Greatest breadth of carapace . . . 7.2 



Length of carapace 6.5 



Breadth of anterior margin of front . 1.55 



Mertonia Laurie. 

 1906. Mertonia Laurie. Rep. Pearl Oyster Fish. Ceylon, prt 5, p. 423. 



This genus comes very near to Xenophthalniodes , as the lateral margins of the carapace 

 are divereine backward ; but the fronto-orbital distance is more than half the greatest breadth 

 of the carapace, the eyes, though minute, are quite distinct, visible in ventral view, and the 

 antennae are unusually long, stout and provided with long, feathered hairs. 



Only one species is known : 



I. Mertonia lanka Laurie. PI. 16, Fig. 2 a. 



[906. Mertonia lanka Laurie. L. c, p. 424, pi. i, f. 11. 



1910. Mertonia lanka Rathbun. K. Dansk. Vid. Selsk. Skr., 7. Raekke, Afd. 5, n" 4, p. 342, 

 pi. 2, f. 4. 



Stat. 273. Pulu Jedan, east coast of Aru Islands. Depth 13 m. i cf- 



69 



