88 
THE VOYAGE OF H.M.S. CHALLENGER. 
<?. 
Lines. 
Millims. 
Length of carapace to base of rostrum, about 
7i 
16 
Length of a rostral spine, about 
n 
3 
Greatest breadth of carapace, about 
14 
Length of a chelipede, ..... 
9 
19 
In a specimen of somewhat larger size the chelipedes are slender, and there are a few 
small tubercles on the upper margin of the palm near to the base. 1 
Mithrax hispidus, var. pleuracanthus, Stimpson. 
Cancer hispidus, Herbst, Naturgesch. der Krabben u. Krebse, Heft 8, p. 247, pL xviii. fig. 100, 
1790. 
Mithrax hispidus, Milne Edwards, Guerin, Mag. de Zool. (Cl. vii.), 1832-38; Hist. Nat. Crust., 
vol. i. p. 322, 1834. 
„ „ A. Milne Edwards, Crust, in Miss. Sci. au Mexique, pt. 5, p. 93, pi. xxi. 
fig. 1, 1875. 
„ pleuracanthus, Stimpson, Bull. Mus. Comp. Zool., vol. ii. p. 116, 1870. 
„ „ A. Milne Edwards, Crust, in Miss. Sci. au Mexique, p. 95, pi. xx. fig. 3, 
1875. 
Brazil, South of Pernambuco, in 30 to 350 fathoms, lat. 9° 5' 0" S. to 9 C 10' 0" S., 
long. 34° 49' 0" W. to 34° 53' 0" W. (Stations 122 to 122c). Two small males. 
In the larger of these specimens the carapace measures only about 6 lines (12'5 mm.) 
in length and breadth, but in all its characters resembles large adults, except in having 
the tubercles of the dorsal surface of the carapace more distinct ; in particular, I may 
note that the accessory spinule of the second and third antero-lateral marginal teeth is 
very distinctly developed. In the smallest specimen (length of carapace little over 3 lines 
or 7 mm.) the accessory spinule is discernible only on the third antero-lateral tooth. 
In another small male specimen from the same locality and depth (length nearly 
4 lines (8 mm.) the carapace is slightly narrower, more distinctly sulcated, and the teeth 
of the antero-lateral margins are all of them simple ; this may belong to a distinct 
species, allied to Mitlirax forceps, from fully grown examples of which it is only 
distinguished by the narrower carapace, or it may even be a variety of that species. 
Mithrax forceps (A. Milne Edwards). 
Mithraculus forceps, A. Milne Edwards, Crust, in Miss. Sci. au Mexique, pt. 5, vol. i. p. 109, 
pi. xxiii. fig. 1, 1875. 
An adult female was obtained at Bermuda on the shore, and another at Bahia in 
shallow water. 
1 By A. Milne Edwards Mithrax acuticornis , Stimpson, is regarded as the young of this species. Stimpson’s 
diagnosis, however, scarcely suffices to determine this point ; specimens which have been referred to Mithrax acuticornis 
in the collection of the British Museum, are distinguished, not merely by the absence of spines from the palms of the 
chelipedes, but also by the non-spinuliferous wrists. Mithrax cornutus is nearly allied to Mithrax spinosissimus, Saussure, 
in the spiniferous palms of the chelipedes and in the distinctly developed spines of the rostrum. 
