142 BULLETIN 129^ UNITED STATES NATIONAL MUSEUM 



Widely distributed on both coasts of middle America; Azores; 

 Cape Verde Islands; Mediterranean; Red Sea; Indian Ocean; 

 Hawaiian Islands. 



Only one American species, which is found on both sides of the 

 continent. 



ACANTHONYX PETTVERII Milne Edwards 



Plate 44; plate 222, figs. 1-6 



Acanthonyx petiverii Milne Edwards, Hist. Nat. Crust., vol. 1, 1834, p. 343 

 (type-locality, Antilles; type in Paris Mus.). — Dana, U.S. Expl. Exped., 

 vol. 13, Crust., pt. 1, 1852, p. 128; 1855, atlas, pi. 5, fig. Qa-d.—A. Milne 

 Edwards, Crust. R6g. Mex., 1878, pi. 27, figs. 7-7/. — Rathbun, Bull. 

 U. S. Fish Comm., vol. 20, for 1900, pt. 2 (1901), p. 60; Proc. U. S. Nat. 

 Mus., vol. 38, 1910, p. 534, pi. 46, fig. 4 (after Milne Edwards and Lucas). 



Acanthonyx emarginatus Milne Edwards and Lucas, d'Orbigny's Voy. 

 l'Am6r. M^rid., vol. 6, pt. 1, 1843, p. 9; atlas, vol. 9, 1847, pi. 5, fig. 2 

 (type-locality, near Lima, Peru; type in Paris Mus.). 



Acanthonyx debilis Dana, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 272 

 (type-locality, Valparaiso, Chile; type not extant); U. S. Expl. Exped., 

 vol. 13, Crust., pt. 1, 1852, p. 127; 1855, atlas, pi. 5, fig. 5 a and h. 



Peltinia scutiformis Dana, Amer. Journ. Sci., ser. 2, vol. 11, 1851, p. 273 

 (type-locality. Bay of Rio Janeiro; type not extant); U. S. Expl. Exped., 

 vol. 13, Crust., pt. 1, 1852, p. 130; 1855, atlas, pi. 5, fig. 7a-c. 



Acanthonyx concamerata Kinahan, Journ. Roy. Dublin Soc, vol. 1, 1857, 

 p. 334, pi. 14, fig. 1 (type-locality. North Cinchas Island, Peru; type in 

 Mus. Roy. Dublin Soc). 



Acanthonyx petiveri Stimpson, Ann. Lye. Nat. Hist. New York, vol. 10, 1871, 

 p. 97.— A. Milne Edwards, Crust. Reg. Mex., 1878, p. 143, and synonymy. 



Pugettia scutiformis^^ Miers, Challenger Rept., vol. 17, 1886, p. 40, foot- 

 note. — MoREiRA, Arch. Mus. Nac. Rio de Janeiro, vol. 11, 1901, pp. 65 

 and 138; Bull. Soc. Zool. France, vol. 45, 1920, p. 126, footnote.— ?Lenz 

 and Strunck, Deutsche Siidpolar Exped. 1901-1903, vol. 15, Zool. 7, 

 1914, p. 276. 



Diagnosis. — Hepatic lobe large; two small branchial lobes. Pre- 

 orbital tooth obtuse. Male abdomen with six segments. 



Description. — Antero-lateral angles subrectangular, obtuse, frontal 

 region triangular. Two small teeth on margin of branchial region. 

 Carapace almost smooth; three obscure setiferous tubercles on 

 gastric region, one on the cardiac and one on the intestinal region; 

 these tubercles are obsolete in the female, but the setae remain. 

 Lateral teeth and rostrum setiferous. Rostrum short, deflexed, 

 bifid. Preorbital lobes obtuse, elevated. Basal article of antennae 

 unarmed, the next two articles subcylindrical, attaining end of 

 rostrum; flagellum very slender. Chelipeds with merus sub triangu- 

 late; carpus with an external crest and two or three setiferous 



26 Dana's Peltinia scutiformis is undoubtedly the young of Acanthonyx petiverii. A young male in the 

 National Museum collection (19066), 5 mm. long, approximately the size of Dana's P. scutiformis, agrees 

 with Dana's colored figure, 7a, U. S. Expl. Exped. atlas, pi. 5, except that the greater part of the yellow 

 spot in the center of the carapace has disappeared. A. Milne Edwards (Crust. R6g. Mex.) comments on 

 the narrowness of the penultimate article of the legs in the young of A petiverii. It is impossible to tell 

 with certainty whether Lenz and Strunck's specimens are the young of petiverii or of an allied species. 



