254 
THE VOYAGE OF H.M.S. CHALLENGER. 
There is probably but a single species of this genus (the common Gulf-Weed Crab), 
which occurs nearly everywhere on floating weed in the temperate and tropical seas of 
the globe, and has been referred to under many different specific names. 
Nautilograpsus minutus (Linne). 
Cancer minutus, Linne, Syst. Nat., ed. xii., p. 1040, 1766. 
Grapsus pusillus, de Haan, Crust, in v. Siebold, Fauna Japonica, pp. 32, 59, pi. xvi. fig. 2, 1835. 
Nautilograpsus minutus, Milne Edwards, Hist. Nat. Crust., vol. ii. p. 90, 1837; Ann. d. Sci. 
Nat., tom. cit., p. 174, 1853. 
,, „ Kingsley, tom. cit., p. 202, 1880, et synonyma. 
The specimens in the collection are from the following localities : — 
Gomera, Canary Islands, February 1, 1873 (an adult male); between Bermuda and 
the Azores, June 20, 1873 (a large series of specimens, attached to Ianthina and other 
floating objects); off Sombrero Island, West Indies, March 15, 1873 (a small female); 
gulf-weed in the North-West Atlantic, April 1873 (numerous specimens); from Fucus in 
the North Atlantic, June 26, 1873 (an adult male and two females); South Pacific, near 
the Kermadec Islands, on the surface, among seaweed, July 15, 1874 (numerous speci- 
mens); North Pacific, off Volcano Island, April 4, 1875, from tube containing surface 
dredgings (a female); coast of Japan, June 1875 (an adult female); North-West Pacific, 
surface, June 1875 (two adult females). 
Specimens of this genus show a considerable degree of variation in the convexity of 
the carapace, the development of the antero-lateral marginal tooth, which is sometimes 
obsolete, in the coloration of the body and limbs, &c., but I cannot find any valid 
characters for the distinction of the numerous supposed species which have been described 
by authors. 
Adult J . Lines. Millims. 
Length and breadth of carapace, i . . . . . .9 19 
Grapsus, Lamarck. 
Gh-apsus, Lamarck (pt.), Syst. Anim. sans Vert., v. p. 247, 1818. 
„ Milne Edwards (pt.), Hist. Nat: Crust., vol. ii. p. 83, 1837; Ann. d. Sci. Nat., 
ser. 3, Zool., vol. xx. p. 166, 1853. 
„ Kingsley, Proc. Acad. Nat. Sci. Philad., p. 192, 1880. 
Carapace depressed, with the cervical sutures strongly defined ; the lateral margins 
regularly arcuated, and armed with a single tooth behind the exterior orbital angle, the 
dorsal surface marked with transverse raised lines, which are strongest on the branchial 
regions ; the front is of moderate width, strongly deflexed, and its anterior margin is 
entire and slightly arcuated; the orbits of moderate size, rather deep, and their inferior 
1 This is rather more than the average size of adult examples, but I have examined yet larger specimens in the 
collection of the British (Natural History) Museum. 
