182 
THE VOYAGE OF H.M.S. CHALLENGER. 
In this specimen the palms and merus-joints of the chelipedes are more elongated 
than in the figure of A. Milne Edwards, and the spine at the distal extremity of the 
posterior margin of the merus-joint is obsolete. The lateral epibranchial spine does not 
at all exceed the preceding spine in length, and in this character, as well as in those of 
the chelipedes, this specimen differs from authentically-named examples of Neptunus 
depressifrons in the collection of the British (Natural History) Museum. It may be 
that these characters will prove, upon examination of a sufficient series, sufficient to 
separate the Bermuda swimming-crab as a distinct species from Neptunus depressifrons. 
B. Neptuni with the spine on the inner margin of the carpus abnormally developed 
(in the adult male exceeding the palm in length) : — 
Subgenus Hellenus, A. Milne Edwards. 
Hellenus, A. Milne Edwards (pt.), Crust, in Miss. Sci. au Mexique, pt. 5, pp. 210, 221, 1879. 
In the single species which follows, to which I propose to restrict this subgenus, 
there is scarcely any trace of a spine or tooth at the postero-lateral angles of the carapace, 
and I am inclined to think that the form of the postero-lateral angles cannot be regarded 
as affording a character of importance sufficient to distinguish the subgenus. 
Neptunus ( Hellenus ) spinicarpus (Stimpson). 
Achelous spinicarjpus, Stimpson, Bull. Mus. Comp. Zool., voL ii. p. 148, 1870. 
Neptunus ( Hellenus ) spinicarpus, A. Milne Edwards, Crust, in Miss. Sci. au Mdxique, pt. 5, 
p. 221, pi. xl. fig. 1, 1879. 
Brazil, off Barra Grande, lat 9° 5' 0" S. to 9° 10' 0" S., long 34° 49' 0" W. to 
34° 53' 0" W., in from 32 to 400 fathoms (Stations 122 to 122c). An adult male and two 
adult and one young females are in the collection. 
In none of the females does the spine on the inner margin of the wrist, although 
greatly developed, reach the distal extremity of the upper margin of the palm; in the 
adult male it is far larger, reaching nearly to the middle of the dactylus, or mobile finger, 
and is considerably dilated and strongly compressed, and bordered on its outer margin 
with a fringe of long hairs ; the carapace also is provided with stronger rounded pro- 
minences on the cardiac and branchial regions in the male than in the females. 
The dimensions of this specimen are as follows : — 
Adult $ . Lines. Millims. 
Length of carapace, . .. . . . . . 8-|- 18 
Breadth to base of lateral epibranchial spine, . . . 12 25 
Length of a chelipede, ...... 22J 45 - 5 
Length of spine on the inner margin of the wrist, . . . 9 19 
Length of first ambulatory leg, . . . . . 17 36 
