24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



than in groove slight or wanting. Anterior margin of epistome armed 

 with three spines, median and pair of laterals. 

 B 1 . Groove very short, inconspicuous, scarcely a sixth of the length of the 



upper margin of palm or less , planissimum (Herbst). 7 



(Naturges. Krabben u. Krebse, vol. 3, pt. 4, p. 3, pi. 59, fig. 3, 1804. 

 Alcock, Journ. Asiatic Soc. Bengal, vol. 69, p. 439, 1900.) 

 B a . Groove longer, about a third (from a fourth to a half) the length of the 



upper margin of the palm gibbesi Milne-Edwards. 



(Ann. Sci Nat., ser. 3, Z00L, vol. 20, pp. 180, 146, 1853. Rathbun, 

 Bull. 97, U. S. Nat. Mus., p. 337, pi. 105, 1918.) 



Gecarcinns planatus Stimpson i,^ 



One of the few land crabs seen. In former years this species was 

 exceedingly abundant on Clipperton. It is possible that the drove of 

 wild pigs loose on the island has so reduced their numbers that they 

 now seem scarce. 



Sulivan Bay, James Island, Galapagos, July 24 (sta. 15-38) ; 

 shore and tide-pool collecting. 



Lepeophtheirus dissimulatus Wilson 1 J 1 55 



Crangon cylindricus Kingsley 1 



Crangon malleator (Dana) 2 



Synalpheus nobili Coutiere 3 



One of three specimens assigned to this species is but tentatively 

 placed here. In many respects it resembles a closely related species, 

 S. sanlucasi. As it does not have the stout legs characteristic of that 

 species, this specimen has been placed here as a variant perhaps of 

 S. nobili. 



7 This species of Pcrcnon and the next are very close and very similar. There 

 is some variation in the length of the pilose groove of the upper margin of the 

 hand. The characteristically short groove of planissimum holds for all speci- 

 mens of more than three-fourths of an inch in width. In some smaller or im- 

 mature specimens, chiefly females, the groove appears relatively longer than 

 in larger, better-developed individuals. Specific distinctions are best exhibited 

 in well-developed males. 



There is another character not referred to in the key that seems to hold for 

 many specimens of either of these two species of Percnon, but not for all unless 

 I am mistaken in some of my identifications. In P. planissimum the teeth of 

 the lateral margin of the carapace, at least those following the one at the antero- 

 lateral angle, are more or less subequal ; the second and third teeth, counting 

 the extra orbital tooth, measured on their outer margins are about of equal 

 length. In P. gibbesi the outer margin of the second lateral tooth, counting the 

 one at the anterolateral angle of the carapace, measured on the outer margin 

 is in general or in many specimens appreciably a little shorter than the third. 



