CETJSTAOEA. 269 



carpus and penultimate joints alternately banded -with yellow and 

 red. 



The type of Leach's P. lamarchii (from Australia) in the Museum 

 collection has lost its chelipedes; hence the identification is not 

 certain ; but the carapace in all respects agrees -with the specimens 

 described above, and there exists a distinct postocular spine on the 

 lateral margins. 



The type specimens of P. asiaticus, from the Mauritius, are of 

 larger size, but scarcely differ except in having the anterior margins 

 of the -wrists armed with more distant, but relatively smaller tt^eth, 

 and in having the distal ends of thq merus-joints of the first and 

 second ambulatory legs more distiactly denticulated. Specimens 

 apparently belonging to this form are in the Museum collection 

 from various islands of the Pacific and Malaysian seas ; and I think 

 it very probable that it should be united with P. Iwmarchii. I 

 may note here that the specimen recently figured by Eichters * as 

 P. asiaticus. Leach (and by him retained in the genus Porcellana), 

 has a more distinctly truncated median frontal lobe, and only two 

 teeth on the posterior margin of the arm of the chelipede, and may 

 perhaps belong to a distinct species. 



13. Petrolisthes haswelli. (Plate XXIX. fig. A.) 



Carapace flattened, longer than broad, and marked with faint 

 transverse strise, which are bordered with short hairs ; the lateral 

 margins are cristated, the carinae extending from the outer orbital 

 angles to about the middle of the branchial regions ; the front is 

 subtriangulate, with the apex rounded and concave above, the 

 margins somewhat sinuated; the outer orbital angle is not very 

 prominent, behind it there is a spine on the hepatic region ; the upper 

 orbital margins are entire. The eyes are short and thick. There 

 is a prominent tooth or lobe upon the antepenultimate joint of the 

 peduncle of the antennae, -v^hose flagella are very long and naked. 

 ■ The chelipedes are moderately robust, the merus or arm very short, 

 with a prominent lobe at the distal end of its inner margin : the 

 carpus is flattened above, its upper surface tuberculated, the tubercles, 

 which in the middle line are generally larger, are flattened and 

 bordered with short hairs ; its anterior margin armed with four or 

 five unequal te.eth, whose margins are themselves generally denticu- 

 lated; the posterior margin armed with three spines at its distal 

 end ; palm and fingers closely tuberculated on their outer surface, 

 the tubercles bordered with short hairs, and merging toward the 

 upper margin into longitudinal striae ; the lower margin of the 

 palm is straight and subcristated ; fingers shorter than the palm, 

 meeting along their inner edges, and incurved at the tips. Ambu- 

 latory legs slightly hairy, with the merus-joint moderately dilated 

 and compressed, without spinules or teeth, except one or two small 

 denticles at the distal end of the lower margin ; the following joints 



* In MobiuB, Beitr. zur Meeresfauna der Ineel Mauritius &c., Decapoda, 

 p. 159, pi. iTii. fig. 13 (1880). 



