RATHBUN— MARINE BRACHYURA 231 



Seychelles, 34 ftns., Sta. F 7 ; 1 $ varying towards the form described below, in 

 having the thumb of the large claw a little longer than is typical and the lower marginal 

 line of granules on the palm very indistinct. 



160. Actumnus setifer amirantensis, subsp. nov. (Plate 16, figs. 12, 13). 



$, type, C. 1. 8*8 mm., C. b. 117 mm., fronto-orbital b. 9"4 mm. 



The most abundant Actumnus in the western Indian Ocean if this collection is 

 an indication. 



Carapace moderately convex ; tomentum short, thick and smooth ; areolations little 

 prominent, well separated, sparingly granulate ; front broader than in A. setifer (de Haan), 

 outer tooth triangular, distinct, and separated by an obliquely angled sinus from the 

 obtuse upper angle of the orbit ; three lateral teeth tipped with a spine. Wrist sparingly 

 granulate, smaller palm sharply granulate. 



The upper part (less than half) of the outer surface of both palms is thinly tomentose ; 

 the sharp granules disappear on the lower distal portion of the large palm ; inner surface 

 smooth and shining ; no inferior marginal line except near the wrist. The fingers are 

 rather long and the immovable fingers deflexed, that of the small claw more deflexed 

 than that of the large claw. 



In small specimens the larger palm has a larger area of granulation than in adults, 

 and the ridge on the immovable finger has a line of granules on its basal half. 



This subspecies, as represented by a lot of 143 specimens from Station E 6, is quite 

 distinct from typical Actumnus setifer. There are before me seven specimens of the 

 latter, from three widely separated localities, Japan, Pulo Edam, and Gulf of Siam. 

 They differ from the subspecies amirantensis, not only in the greater convexity of the 

 carapace and its areoles, as mentioned by Alcock in comparing it with A. tomentosus Dana, 

 but in the more granulated palm, shorter fingers, more horizontal thumb, and the inferior 

 marginal line of granules separating the outer from the inner surface of the palm. 

 Our subspecies is also smaller, the largest specimens averaging about 12 mm. in 

 width. 



The subspecies was obtained at 1 9 different stations, and at some of these there 

 are specimens which incline toward typical A. setifer. These variations are indicated 

 below in the list of localities. 



Cargados Carajos, 30 fins., Sta. B 8 ; 2 $, 1 juv. ; the largest ,f, about 13 mm. wide, 

 approaches the convexity in carapace and areolae of A. setifer; chelipeds lacking : 30 fins., 

 Sta. B 14 ; 1 $, 1 ? : 30 fins., Sta. B 15 ; 8 $, 6 ? : 30 fins., Sta. B 16 ; 1 $ juv. : 30 fins., 

 Sta. B 17 ; 1 $, 1 ?, 1 juv. ; the $ about 11 '5 mm. wide varies toward A. setifer, that is, 

 the outer surface of the larger palm is nearly all granulate, the immovable finger is 

 shorter, but not so short as in A. setifer, there is an inferior line of granules on the 

 proximal half of the palm. Saya de Malha, 47 fins., Sta. C 12; 1 $ without chelipeds: 

 55 fins., Sta. C 15 ; 1 $, 2 ?, 1 juv. ; $, C. b. 14 mm. Providence, 70 fins., Sta. D 7 ; 1 ?. 

 Amirante, 29 fins., Sta. El; 7 <?, 11 ? (8 ovig.) ; vary toward A. setifer, several specimens 

 having a short thumb, the lower part of palm chiefly bare, but with a few scattered 

 granules and granules on the proximal end of the ridge on the thumb : 29 fins., Sta. E 2 ; 

 SECOND SERIES— ZOOLOGY, VOL. XTV. 30 



