230 Dr. W. T. Caiman on a new Species of 



indebted to Prof. M'Intosh for allowing this precious and 

 fraoile specimen to run the risks of a journey to London, in 

 order that I might compare it directly wiik the l Challenger' 

 type. The result has been to show that the West-Indian 

 and Japanese forms are quite distinct, though closely allied, 

 species. Brief summaries of their distinctive characters are 

 given below, followed by some more detailed notes on the 

 St. Andrews specimen. 



Thaumastocheles zaleucus (Willemoes-Suhm). 



Astacus zaleucus, Willemoes-Suhm, in Wyville Thomson, Nature, viii. 



1873, p. 247, fig-. 1 ; Milne-Edwards, Ann. Sci. Nat., Zool. (5) xix. 



1874, Art. 7, 2 pp., pi. xx. ; Willemoes-Suhm, Trans. Linn. Soc. 

 London, ser. 2, Zool. i. 1875, p. 48, pi. x. fig. 1. 



Thaumastocheles zaleucus, Wood-Mason, Proc. Asiatic Soc. Bengal, 

 1874, p. 181 ; Spence Bate, Rep. ' Challenger' Macrura, 1888, p. 47, 

 pis. vi., vii. fig. 1. 



Third segment of antennular peduncle more than 1^ times 

 as long as second, its width less than half of its length. 

 Penultimate segment of antennal peduncle extending well 

 beyond tip of scale, more than twice as long as distal segment. 

 Spiniform teeth on fingers of larger cheliped inclined alter- 

 nately to either side of the plane in which the ringers lie. 

 Palm of smaller cheliped more than half as long as fingers. 

 Dactylus of second and third peraaopods two-thirds of length 

 of upper border of palm. 



Holotype: female, total length (rostrum to telson) 110 mm., 

 from ' Challenger ' Station 23, off Sombrero Island, West 

 Indies, 450 fathoms (Brit. Mus. Crustacea, reg. no. 88. 22). 

 Paratype : chelipeds (first pair) and left third maxilliped of 

 another individual from the same locality. 



Thaumastocheles japonicus, sp. n. 



Thaumastocheles zaleucus, Doflein, Zool. Anz. xxx. 1906, p. 521, 

 figs. 1-4 ; Rathhun, Bull. Mus. Comp. Zool. Harvard, lii. 1910, p. 314, 

 pi. vi. 



Third segment of antennular peduncle hardly longer than 

 second, its width more than two-thirds of its length. Penulti- 

 mate segment of antennal peduncle just reaching tip of scale, 

 one and a half times as long as distal segment. Spiniform 

 teeth on fingers of larger cheliped lying in the plane of the 

 fingers. Palm of smaller cheliped less than half as long as 

 the fingers. Dactylus o£ second and third peraeopcds equal 

 or nearly so to upper border of palm. 



Holotype: female, total length 17-4 mm., in Zoological 



