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PseudograpsUS H. Milne-Edwards. 



1837. Pseiidograpsus (part.) H. Milne-Edwards. Hist. Nat. Crust., t. 2, p. 81. 



nee Pscudograpsiis Dana. Proc. Ac. Nat. Sc. Philadelphia, 185 i, p. 248 (= i);'(7(;/!j///<?/«.f). 



Psejidograpsus is nearly related to Ptychognathus and to Brackynotiis (^ Heterograpsus). 

 From the former genus it is distinguished by the exognath of the external maxillipeds being, 

 even in the cf, -much narrower than the ischium; from Brachynotus by the merus of these 

 maxillipeds being slightly auricular, not subquadrate. Besides, the antero-lateral teeth of the 

 carapace are separated by partly closed fissures, not open sinuses, in Psezidograpsus, but nearly 

 always defined by triangular, sometimes even very deep, incisions in the two other genera. 



Notwithstanding the said difference between the meri of the external maxillipeds of 

 Pseitdograpsus and Brachynotus, it remains a matter of difficulty to separate the genera. 

 Comparing f. i. the external maxilliped of Ps. erythraeus Kossmann ^), which has been referred 

 by the author himself and by Nobili -) to Pscudograpsiis, but by Kingsley ') to Heterograpsus 

 (= Brachynotus) we may observe, that in this species the merus is even less auriculate than 

 in the case of Brach. elongatus A. Milne-Edwards as depicted by Miss Rathbun *), whereas 

 we should expect the reverse to be the case. For the rest it is not unlikely, that, notwith- 

 standing the localities are widely distant from each other (Red Sea and Pacific Islands) the 

 two species are identical, as they agree in all important particulars; in Milne-Edwards' species 

 only the carapace is more narrowed posteriorly. 



The "Siboga" collected a small species of Pseudograpsus, that I am not able to refer 

 to any of the known .species, besides two already known ones of the genus. 



Key to the species : 



1. Large species (carapace attaining a breadth ot 40 mm. and 



even more) of a chestnut colour. Cervical groove very 

 deep, semi-circular. Three last joints of walking legs thickly 

 clothed with a short, velvety fur of black hairs .... 2 

 Small species (carapace attaining a breadth of about i 5 mm.) 

 of a white colour. Cervical groove indistinct, nearly straight. 

 Three last joints of walking legs naked 3 



2. Postero-lateral margins of carapace not sharp, disappearing 



backward. Outer surface of chela (of cf) near base of fingers 

 with a tuft of very long, black hairs. Anterior margins of 

 walking legs heavily fringed Ps. setosus (Fabricius) ') 



1) Zool. Erg. Reise Kiistengeb. d. Roten Meeies, Bd I, 1877, pi. 3, f. 15. 



2) Ann. Sc. Nat. (9) t. 4, 1906, p. 321. 



3) Proc. Ac. Nat. Sc. Philadelphia, 1880, p. 209. 



' 4) Hi'iiiigrapsiis elongatus, Mem. Mus. comp. Zool. Harvard Coll., v. 35, n" 2, 1907, pi. 7, f. 2. 



5) literature: Kingsley, Proc. Ac. Nat. Sc. Philadelphia, iSSo, p. 205. Rumi'Hius already knew this species, designating it 

 as "■Cancer barbatus''' (Amboinsche Rariteitkamer, 1705, p. 26, pi. 10, n" 2) and it has been generally referred to under the latter name, 

 but this name is inadmissable, being pre-Linnean. Distinct localities of this apparently fluviatile species are given by Heller (Reise 

 "Novara", Crust., 1865, p. 52, Nicobars) and DE Man (Weber's zool. Erg. Reise niederl. Ost-Indien, Bd 2, 1892, p. 317, Flores, and 

 Abhandl. Senckenb. Gesellsch., Bd 25, Heft 3, 1902, p. 506, Ternate). The Leiden Museum possesses a fine q' collected at Amboyna 

 by LUDEKING (1864). 



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SIBOGA-EXPEDITIE XXXIX c. 1% 



