180 
THE VOYAGE OF H.M.S. CHALLENGER. 
An adult male measures as follows 
Adult $ . 
Lines. 
Millims. 
Length of carapace, ..... 
11 
23-5 
Breadth to base of lateral epibranchial spine, . 
15J 
32-5 
This species, together with Neptunus [ Achelous ) spinimanus and Neptunus uni- 
spinosus, might be placed with almost equal justice in the subgenus Amphitrite, since 
in these forms the lateral epibranchial spine is distinctly longer than the preceding. 1 
Neptunus [Achelous) granulatus (Milne Edwards). 
Lupa granulata, Milne Edwards, Hist. Nat. Crust., vol. i. p. 454, 1834. 
Portunus ( Amphitrite ) gladiator, de Haan (not Eabricius), Crust, in v. Siebold, Fauna Japonica, p. 65, 
pi. xviii. tig. 1, 1837; not p. 39, pi. i. fig. 5. 
Achelous granulatus, A. Milne Edwards, Archiv. Mus. Hist. Nat., vol. x. p. 344, 1861, et synonyma. 
Samboangan, Philippines, 10 fathoms (a male); Admiralty Islands, 16 to 25 fathoms 
(a male). 
$ . Lines. Millims. 
Length of carapace, . . . . . . . 15'5 
Breadth to base of lateral epibranchial spine, . . . . 9| 20'5 
Neptunus [Achelous) unispinosus (Miers). 
Achelous granulatus, var. unispinosus, Miers, Crust, in Rep. Zool. Coll. H.M.S. “Alert,” p. 230, 
pi. xxiii. fig. B, 1884. 
The carapace is rather narrow and moderately convex, with obscure rounded pro- 
minences which are granulated, and is everywhere covered with a short close pubescence ; 
the postero-lateral angles are rounded. The front is six-toothed ; the median and sub- 
median somewhat more prominent than the lateral teeth, the median teeth smaller, but 
not less prominent than the submedian teeth ; all are distally rounded, not acute at the 
apices. The antero-lateral marginal teeth are small and acute ; the lateral epibranchial 
spine small, but very distinctly longer than the preceding antero-lateral teeth. The 
post-abdomen of the male is composed of five to seven distinct segments, and is 
narrowed from the base of the penultimate segment ; the eyes are large, and are borne 
on very short peduncles. The basal antennal joint is short and rather broad, but 
reaches the lateral subfrontal process ; the ischium-joint of the outer maxillipedes is 
longitudinally sulcated ; the merus subtruncated at its distal extremity. The chelipedes 
(in the male) are subequal and rather short ; the merus-joint (arm) has three or four 
1 In a small specimen of Achelous whitei in the collection of the British (Natural History) Museum, the lateral 
spine is as long as in many species of the subgenus Amphitrite. I prefer, however, to retain these species in the position 
assigned to them by A. Milne Edwards for this reason, if for no other, that were Amphitrite spinimanus removed from 
Achelous it would be necessary to rename this subgenus, of which it is the original type. 
