540 DR. J. G. DE MAN ON CRUSTACEANS [ Dec. 12, 
barbatus A. M.-Edw. *, 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 
related form. As regards 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 
carapace of barbatus is slightly broader in proportion to its length 
than that of pusillus (de Man, J. ¢. p. 104). At all ages, how- 
ever, both in the male and in the female, the cephalothorax of 
barbatus is anteriorly distinctly broader in proportion to 1ts 
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 Péych. pusillus than 
in Ptych. barbatus (figs. 1 and 6). In proportion to the greatest 
width of the carapace the front appears @ 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. barbatus the epigastric lobes 
are situated farther from the frontal border than in pusillus 
(figs. 1 and 6). In Péiych. barbatus the 2nd and the 3rd antero- 
lateral teeth of the carapace are more saliené and the incisions are 
deeper than in pusillus; near the antero-lateral teeth the carapace 
of pusillus is somewhat granulated, but in barbatus not. 
The exognath of the external maxillipedes of the adult male of 
Ptych. barbatus is one-third broader than the ischium, and im the 
adult female it is just as broad or even very slightly broader than 
the ischium; in the adult male of pusillus the exognath appears 
a little less broad in proportion to the ischium, and in the female 
the ischium is decidedly broader than the exognath. 
The slight differences 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. Péych. barbatus is smaller than pusillus 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 Wukur, on the island of Flores, is lying before me (vide 
de Man, in Max Weber’s ‘Decapoden des Indischen Archipels,’ 
1892, p. 317); it will be useful to indicate the differences between 
this specimen and the female of Ptych. pusillus Heller, since they 
much resemble each other. Both species, of course, differ at 
first sight by their external maxillipedes; the rounded antero- 
external angle of the merus-joint is less strongly produced in 
Pseudograpsus barbatus than in Heller's species, and the exognath 
* Ptych. barbatus 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, lxix. (2) no. 3, 1900, p. 406. 
