542 DR. J. G. DE MAN ON CRUSTACEANS [ Dec. 12, 
- 6. Ptychognathus intermedius de M. 1879. ¢. 
7 
: Bi dentatus de M. 1892. o¢ Q@. 
8. 5 spinicarpus Ortm. 1894. ¢. 
¥). as polleni de M. 1895. ¢. 
10. 7 afinis de M. 1895. ¢. 
ll. 5 onyx Alcock 1900. o. 
I, 7 andamanicus Alcock 1900. @. 
Of all these species the male is known, except of Ptych. anda- 
manicus Aleock, which is, however, probably identical with 
Ptych. riedelii A. M.-Kidw.; of five species only has the female 
been observed. 
According to their outer appearance and physiognomy these 
12 species may be divided into three natural sections. The first 
section represented by five species, viz. Ptych. dentatus, spinicarpus, 
polleni, affinis, and onyx, of which Ptych. dentatus is the typical 
form, is distinguished by the following characters :—-The carapace 
is hardly broader than long, the regions usually quite distinct, as 
also the epigastric lobes. The three teeth of the antero-lateral 
margins are sharp and salient. Front prominent, laminar, 
straight, or nearly straight. Inner angle of the carpus of the 
chelipedes produced, in the male, to form a more or less long 
spine, except in Piych. dentatus, in which the inner angle is acute, 
but not spiniform. Chel glabrous on their outer surface, except 
in Ptych. onyx, in which there is a tuft of hair in the finger-cleft 
and extending along the fixed finger. Ambulatory legs hairy, 
the anterior border of the merus with a subterminal spine. 
The second section is composed of Ptych. glaber, riedelii, with 
its variety pilosa, and Ptych. andamanicus; Plych. riedelii may 
be regarded as the type. The carapace of Ptych. riedeli and 
andamanicus is hardly broader than long, that of glaber, however, 
is distinctly broader than long. The upper surface is quite flat, 
much depressed, the regions are not or hardly indicated, and the 
epigastric lobes are wanting. There are two teeth behind the 
extraorbital angle, as in the two other sections, or one (glaber) ; 
the teeth are small, not very acute or distinct. Front prominent, 
laminar, slightly sinuous, furrowed transversely. Inner angle of 
the carpus of the chelipedes obtuse, rounded, or (in Ptych. anda- 
manicus) pronounced, though not spiniform. A brush of stiffish 
hair at the tip of the fixed finger on its outer surface, except in 
Piych. glaber ; chelz for the rest glabrous, except in Ptych. riedelu 
var. pilosa. Ambulatory legs hairy ; subterminal tooth on the 
anterior border of the merus inconspicuous or blunt. 
The third section is represented by four species, viz. Péych. 
pusillus, pilipes, barbatus, and intermedius, of which pusillus 
may be regarded as the type. The carapace is decidedly broader 
than long, flat, though not much depressed. Regions more or 
less distinct, as also the epigastric lobes. Front not prominent, 
distinctly sinuous, and transversely ridged. The three antero- 
lateral teeth are not very conspicuous. Inner angle of the carpus 
