1901.] CBUSTACKA OF THE " SKEAT EXPEDITION.*' 557 



iuuer uropodal joint. It resembles it in the general smoothness of 

 the chelipedes, the length of the telson, and apparently the shape 

 of tlie propodite of the 3rd pair of legs {f. c. p. 482, " Das vqrletzte 

 Glied des dritten Eusspaarer ist oval.") 



Length of auimal 31-5 mm, ; length of carapace 7'25 mm. 



XXXVI. Genus Aectus Dana. 



61. Akgtus tubebculatus Sp. Bate. 



Arctus tuber cidatus, Sp. Bate, ' Challenger ' Macrura, p. 70, 

 pi. X. figs. 1-2 (1888). 



Loc. Kelantan. 



A male and a female, quite agreeing in general with the original 

 description and figure ; but the following points may be noted ; — 

 The tubercle on the 3rd abdominal segment is not quite so clearly 

 separated from its base as it is in Spence Bate's figure ; the coxal 

 plates of abdominal segments 3-5 bear a low ridge, lying trans- 

 versely to the long axis of the body — this is found down the middle 

 of the plate in segment 5, but in the anterior half in segments 3-4, 

 and divides an anterior smooth from a posterior, short-hair}^, 

 surface. The smooth anterior surface plays under the posterior 

 surface of the preceding segment, and the ridge determines the limit 

 Avithin Mhieh this play is possible in complete flexion of the tail. 

 In the 2nd abdomhial segment this ridge is represented by a short 

 line of low tubercles, and the ^^hole surface is hairy. 



XXXVII. Genus Thenus Leach. 



62. Thenus oiiie?^talis Eabr. 



ScjjUarus onentalis, Fabr. Eat. Syst., Suppl. p. 399 (1798) ; 

 Milne-Edwards, Hist. Xat. Crust, ii. p. 2SG (1837). 



Loc. Kelantan ; Trengganu. 



Two males and a female ; all three are infested with a stalked 

 Cirripede on the mouth-parts, notably on the exopodites of the 2nd 

 maxillipedes. This Cirripede belongs to the genus Dichelaspis, and 

 will be described, as a new species of that genus, in the second 

 part of this paper. 



Length; c? 134 mm., c5 420 mm., $ 104 mm. 



XXXVIII. Genus Senex Pfeffer. 



63. SejVex orkaxus Eabr,, var. uov. LyEtis. 



Cf. Senex ornatus, Ortmann, Zool. Jahrb. vi. p. 34 (1892). 



Loc. Singora. 



One full-grown male, just over 1 foot in l(?ngth. 



Although undoubtedly referable to this specie?, this specimen 

 presents such well-marked differences that I haye.thought it Avorth 

 while detailing them and attaching a varietal name thereto. The 

 amount of variation in the species of this genus is evidently very 



Pboc. Zool. Soc— 1001, Vol. II. No. XXXVII. 37 



