OCR Text |
Show 5 4 2 DR. J. G. DE MAN ON CRUSTACEANS [Dec. 12, 6 Ptychognathus intermedins de M. 1879. 3 . 7. ,, dentatus de M. 1892. 3 ? • 8 . ,, spinicarpus Ortm. 1894. 3 . 9. „ polleni de M. 1895. J . 10. „ affinis de M. 1895. 3 • 11. ,, onyx Alcock 1900. J . 12. ,, andamanicus Alcock 1900. $ . Of all these species the male is known, except of Ptych. andamanicus Alcock, which is, however, probably identical with Ptych. nedelii A. M.-Edw.; 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 Ptych. dentatus, in which the inner angle is acute, but not spiniform. Chela? 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. andamanicusPtych. riedelii may be regarded as the type. The carapace of Ptych. riedelii 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. andamanicus) pronounced, though not spiniform. A brush 'of stiffish hair at the tip of the fixed finger on its outer surface, except in Ptych. glaber ; chela? for the rest glabrous, except in Ptych. riedelii var. pdosa. Ambulatory legs hairy ; subterminal tooth on the anterior border of the merus inconspicuous or blunt. The third section is represented by four species, viz. Ptych. 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 anterolateral teeth are not very conspicuous. Inner angle of the carpus |