EEPOET ON THE BEACHYUEA. 
181 
spinules on its anterior margin, and one at the distal extremity of its posterior margin ; 
the wrist has a small spinule on its inner margin and another on its outer surface ; the 
palm is longitudinally costated on its upper and outer surface, and is armed with two 
small spinules, one, basal, near the articulation with the wrist, and one close to the 
distal end of the upper margin, near the ’ articulation with the dactylus ; the dactyl 
and pollex are barely as long as the palm and are denticulated on their inner margins. 
The ambulatory legs are very slender and compressed ; the dactyli longer than the 
penultimate joint ; the posterior or swimming legs are of moderate length, their merus- 
joints smooth, without spinules, the terminal joints rather narrow, ovate. Colour (in 
spirit) light yellowdsh-brown, the pubescence whitish. The dimensions of a Challenger 
specimen are : — 
8. 
Lines. 
Millims. 
Length of carapace, nearly ..... 
6 
12 
Breadth to base of lateral epibranchial spine, nearly . 
8 
16-5 
Length of a chelipede, ..... 
11 
23 
Length of first ambulatory leg, about 
H 
20-5 
Two small males were collected in the Torres Strait, one of these at Station 186, in 
8 fathoms, lat. 10° 30' 0" S., long. 142° 18' 0" E. 
This species is not easily confounded with any of its Oriental congeners. From 
Neptunus ( Achelous ) granulatus, as I have shown, it is distinguished by having but a 
single spine on the posterior margin of the arm, by the less spiniform antero-lateral 
marginal teeth, &c. Its nearest ally in the subgenus Achelous is apparently the 
American Neptunus ( Achelous ) depressifrons ; in which species, however, the lateral 
epibranchial spine is shorter, and the spine on the upper margin of the palm of the 
chelipedes is placed further back from the distal extremity, &c. From such species of 
the subgenus Amphitrite (also American), as are allied to it in the rounded postero- 
lateral angles of the carapace, unarmed merus-joint of the swimming legs, &c. ( e.g . 
Neptunus ( Amphitrite ) gibbesii), it is distinguished by the form of the frontal teeth, and 
the shorter lateral epibranchial spine. 
Neptunus {Achelous) depressifrons (Stimpson). 
Amphitrite depressifrons , Stimpson, Ann. Lyc. Nat. Hist. New York, vol. vii. p. 58, 1859. 
Achelous depressifrons, Stimpson, tom. cit., p. 223, 1860. 
„ „ A. Milne Edwards, Archiv. Mus. Hist. Nat., vol. x. p. 342, 1861; Crust. 
in Miss. Sci. au Mexique, pt. 5, p. 230, pi. xl. fig. 4, 1879. 
Bermuda (shore). An adult male. 
Adult 8 • Lines. Millims. 
Length of carapace, nearly . . . . . . 7 14 ‘5 
Breadth of carapace to base of lateral epibranchial spine, nearly . 9J 19 ‘5 
