366 Dr. W. T. Caiman on a 



XLIV. — Note on a Crayfish from New Guinea. 

 By W. T. CalmAxV, D.Sc. 



(Publislied by permission of the Trustees of the British Museum.) 



Among tlie Crustacea collected by the British Ornitho- 

 logists' Union Expedition to New Guinea are nine specimens 

 of cra}?fisli from the Mimika River, the characters of which 

 seem to cast doubt on the validity of some of the species 

 that have been described from thxa part of the world. 



The following is a list of the species hitherto recorded 

 from New Guinea and adjacent islands : — 



Chera]>s alhertisii [■= Asia conephr ops alhertiaii, Nobili}. 



Katau, near mouth of Fly liiver *. 

 C. lorentzi, Roux. Manikiou District ; Etna Bay; 



Sabang on the Lorentz (Noorcl) Kiver t« 

 C. aruanus, Roux. Anu Islands J. 

 Astacopsis australasiensis (H. Milne-Edwards). Soroiii^ 



Island, Galewo Strait §. 



In the case of the last of these species some doubt may 

 still be entertained as to the locality, on account of its 

 remoteness from the type-locality of the species (Sydney). 

 The remaining species are all very closely related, as Roux 

 has shown, to Ckeraps quadricarinatus (v. Martens) ||, the 

 unique type-specimen of which came from Cape York. 

 C. alhertisii, also known only from a single specimen, differs 

 from the others in having three, instead of two, pairs of 

 spinules on the rostrum, a character to which Dr. Roux very 

 justl}' attributes only a provisional value. Apart from this, 

 the species are distinguished solely on the ground of differ- 

 ences in the proportions of the chelre. Such characters are 

 known, in other crayfishes, to vary greatly according to 

 sex and age, and Dr. Roux was only led to attribute specific 

 value to tiiem in this case from the " fixite remarquable '"' 

 observed in the proportions of the chelie in specimens of the 



* Nobili, Aun. Mus. Civ. St. Nat. Geneva, xl. 1899, p. 244, and Boll. 

 Mas. Zool. Torino, xviii. No. 445, 1903, p. 1, iip:. ; Koux, Zool. Auz. 

 xxxvii. 1911, p. 104, and Notes Leydon Mus. xxxiii. 1911, p. 98. 



t lioux. Notes Leydon Mus. xxxiii. 1911, p. 97, tigs. 4 & o. 



I Koux, f. c. p. N^, ti-rs. '2 Sc 3. 



§ Nobili, Aun. Mus. Civ. St. Nat. Geuova, xl. 189.1. p. -Jie. and Boll. 

 Mus. Zool. Torino, xviii. No. 445, 190:$, p. 2. 



II MB. Ak. Wiss. Berlin, 18(38 (18(39), p. 617. 



