RIJKS MUSEUM VAN NATUURLIJKE HISTORIE — LEIDEN. 167 



XII. - THE GRAPSOID GENUS PYXIDOGNATHUS A. MILNE- 

 ED WARDS, WITH DESCRIPTION OF A NEW SPECIES. 

 BY Dr. J. J. TESCH. — (with plate xi). 



The genus Pyxidognathus was established by A. Milne-Edwards (Bull. 

 Soc. Philom. Paris, ser. 7, t. 3, 1878, p. 109) on a species, named by him 

 P. granulosus, that was found in fresh or slightly brackish water in the 

 island of Ovalau. A few months afterwards, in April 1879, de Man de- 

 scribed a specimen under the name Hypsilograpsus deldeni nov. gen. 

 nov. spec. (Notes Leyden Mus., v. 1, p. 72), collected by van Delden in 

 1836 near Manado (Celebes); this specimen, however, was recognized by 

 de Man himself (Notes Leyden Mus., v. 5, 1883, p. 159) as being probably 

 identical with the species of Milne-Edwards, having had the opportunity 

 of examining an original drawing of the animal, prepared by the French 

 author. 



Dr. de Man has, on my request, kindly sent me this drawing, and 

 after a careful comparison between this and the original Hypsilograpsus 

 specimen, I am fully convinced that the specimens of Milne-Edwards 

 and of de Man belong really to the same species, and that the name 

 Pyxidognathus therefore has priority. 



In 1888 de Man made known another species of this genus, P. deianira 

 (Journ. Linn. Soc. London, v. 22, p. 148, pi. 10, f. 4 — 6), observed in 

 mangrove-swamps of the Mergui Archipelago, and finally Alcock described 

 a third species P. fluviatilis (Journ. As. Soc. Bengal, v. 69, prt 2, 1900, 

 p. 408, 111. Zool. „Investigator", Crust., prt 10, 1902, pi. 66, f. 3— 3a), 

 collected in fresh water in the Jessore District (British India). 



The discovery of a new species, referable to this genus, in a collection 

 belonging to the Amsterdam Zoological Museum, induced me to give an 

 account of Pyxidognathus, the more readily because I could not only 

 provide a drawing of the type species (the original specimen of Hypsilo- 

 grapsus deldeni still being present in our Museum), no figure of which 

 has as yet been published, but also examine an adult male of P. deianira, 

 that was still unknown in the full-grown state. 



Both Milne-Edwards and de Man perfectly recognized the close relat- 

 ionship of Pyxidognathus to Ptychognathus Stimpson (= Gnathograpsus 

 A. Milne-Edwards) ; indeed, among the Grapsidae, both genera are disting- 

 uished by the exognath of the external maxillipeds being as broad as, or 

 even broader than, the ischium. But whereas in Ptychognathus the cara- 

 pace is thin and flattened, the front horizontal, and the chelae are often 

 provided externally with a tuft of hairs, the carapace is thicker and much 



