1901.] CKUSTAOEA Of THE " SKEAT EXPEDITIOS"." 571 



part of it which lies on the first of these four segments being 

 oTdovecl on its upper surface, those parts which lie on the last 

 three ending each in a very distinct tooth. Secondly, there are 

 only three lateral spines on the telsou, of which the posterior two 

 are nearly three times as long as the first. 



84. Pen^eus oanaliculatus Olivier, var. "? (^Plate XXXIV. 

 fig. 5.) 



Penceiis canaliculatus, Oliv. Encycl. Meth. viii. p. 660 (1807); Sp. 

 Bate, ' Challenger ' Macrura, p. 243, pi, xxxii. fig. 1 (1888). 



Loc. Pulau Bidan, Penang. 



Two females and a male. Length : d 58 mm., 5 59 mm., 2 

 50*5 mm. 



The form of the petasma agrees with that of the species, but 

 the form of the thelycum differs from that of the species and of 

 the varieties figured by Spence Bate (t. c. pi. xxxii. figs. 3 and 4). 

 The thelycum proper is nearly like that of the species, but there 

 is an additional plate between the 4th pair of legs and no plate 

 between the 3rd pair (c/. fig. 5). I have not given a distinct name 

 to this form, as it has seemed to me that too little is known 

 about the thelycum, and its possibly seasonal varieties within 

 the same species, to justify the founding of a new variety on this 

 character. 



The telson in these specimens is armed laterally with three 

 teeth, as in P. caramote Eisso, and in the varieties japoaicus and 

 aastralicnsis 8peuce Bate ; but the absence of a strong spine on the 

 i>rd pair of legs distinguishes it from F. caramote, and the form of 

 the thelycum from Spence Bate's varieties. 



85, Pen^eus breticoknis M.-Edw. 



Pencms brevicornis, iVE.-Edw. Hist. Nat. Crust, ii. p. 417(1837); 

 8p. Bate, Ann. Mag. Nat. Hist. (5) viii. p. 180, pi. xi. fig. 2 

 (1881). 



Loc. Patani. A female ; length 70 mm. 



86. PEN.EUS sp. ? (Plate XXXIV. tig. 7.) 



Loc. Patani. 



A male, of 56 mm. length, wliose specific position I cannot 

 determine with any certainty ; for, though agreeing remarkably 

 with the last species (P. hrevicorms), it still presents two features 

 which would seem sufficient to separate it from the latter. Its 

 general form and the shape of the petasma, which agrees with the 

 figure given by Spence Bate of that of P. hrevicorms (1. c. supra), 

 Jed me at first to regard it as belonging to that species, but a closer 

 examination showed the following notable distinctions: — (a) the 

 rostrum barely reaches the tips of the eyes, instead of being just 

 a little longer than these, and it is less raised in its proximal 

 portion over the base of the eye ; (6) the peduncles of the anten- 

 nules reach to the ends of the autennal scales, and their ilagella 



