540 DR. J. G. DB MAN ON CRUSTACEANS [DeC. 12, 



bcii'baUts A. M.-Eclw. *, a marine crab from New Caledonia, which 

 has also been observed on the shores of Atjeh, Penang, and of 

 the islands between Japan and Formosa, is the most closely 

 I'elated form. As regai'ds the proportion between the length of 

 the carapace and the greatest width of it in adult specimens, both 

 species fully agree with one another, but in young individuals the 

 cai'apace of barhatus is slightly broader in proportion to its length 

 than that of pusilhos (de Man, I. c. p. 104). At all ages, how- 

 ever, both in the male and in the female, the cephalothorax of 

 barbatus is anteriorly distinctly broader in pi'oportion to its 

 length, as is proved by comparing the measurements of the length 

 of the carapace and of the distance between the extraorbital 

 angles ; the extraorbital teeth run therefore more obliquely with 

 regard to the median line of the carapace in Ptych. pusilhts than 

 in Ptych. Jxm-batus (figs. 1 and 6). In proportion to the greatest 

 width of the carapace the front appeal's a little broader in barbatus ; 

 it has the same form in both species, but the granulated line that 

 runs immediately behind the frontal margin is, in the middle 

 line of the carapace, contiguous to that margin in barbatus, 

 whereas in Heller's species (fig. 2) both lines are distant from one 

 another in the middle. In Ptych. barbatits the epigastric lobes 

 are situated farther from the frontal border than in pusillus 

 (figs. 1 and 6). In Ptych. barbatus the 2nd and the 3rd antero- 

 lateral teeth of the carapace are 7nore salient and the incisions are 

 deeper than in pusillus ; near the antero-lateral teeth the carapace 

 of 2^usilhis is somewhat gramdatedj but in barbatus not. 



The exognath of the external maxillij)edes of the adult male of 

 Ptych. barbafAcs is one-third broader than the ischium, and in the 

 adult female it is just as broad or even A^ery slightly bi'oader than 

 the ischium ; in the adult male of pusillus the exognath appears 

 a little less broad in proportion to the ischiiuii, and in the female 

 the ischium is decidedly broader than the exognath. 



The slight difl:erences exhibited by the legs are of little im- 

 portance. But for a few hairs on the outer side of the tip of the 

 fixed finger in the female, the extremities of the fingers of barbatus 

 are glabrous. Ptych. barbatus is smaller than pmsillus and the 

 habitat is different, the former being probably a marine species, 

 the latter a freshwater one. 



An adult female of Pseudograpsus barbatus Rumph from the 

 River Wu.kur, on the island of Flores, is lying before me {vide 

 de Man, in Max Webei''s ' Decapoden des Indischen Archipels,' 

 1892, p. 317) ; it will be useful to indicate the diflferences between 

 this specimen and the female of Ptych. pusillus Heller, since they 

 much resemble each other. Both species, of course, difier at 

 first sight by their external maxillipedes ; the rounded antero- 

 exter-nal angle of the merus- joint is less strongly produced in 

 Pseudograpsus barbatus than in Heller's species, and the exognath 



* Pti/ch. harbatns is also described in Prof. Alcock's work : " Materials for a 

 Carcinological Fauna of India. — No. 6. The Brachyura Catometopa or Grapsoidea," 

 Journ. Asiatic Soc. Bengal, Ixix. (2) no. 3, 1900, p. 406. 



