222 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



the species in the Northern Hemisphere and the only recorded occur- 

 rence of the species in Pacific waters north of Chile, Atlantic records for 

 Leucippa pentagona being confined to southern Brazil and Argentina. 

 From the limited history of the species in the Pacific, which aside 

 from the Mexican record includes only Milne Edwards's type specimen 

 from Chile, it is not possible to decide whether Leucippa pentagona is an 

 Austral species communicating with the Atlantic via the Strait of Magel- 

 lan, as suggested by the Hassler specimen from San Antonio Bay (Rath- 

 bun, 1925), or the Pacific member of an analogous species pair. In the 

 former case the Lower California record is distinctly extralimital ; in 

 the latter case the Pacific range, Lower California to Chile, would not be 

 exceptional. Should the latter eventuality prove to be the case, the name 

 L. pentagona would remain with the Pacific member of the species pair, 

 because of the Chilean type locality. 



Genus ACANTHONYX Latreille 



Acanthonyx Latreille, 1825, p. 698; 1829, p. 58. Milne Edwards, 1834, 



p. 342. A. Milne Edwards, 1878, p. 142. Miers, 1879c, p. 650; 



1886, p. 42. Alcock, 1895, p. 198. Rathbun, 1901, p. 60; 1925, p. 



141. 

 Peltinia Dana (part), 1851a, p. 272; 1851b, p. 433; 1852, pp. 84, 129; 



1853, p. 1422. 

 Type: The Mediterranean and eastern Atlantic Maia lunulata Risso, 

 1816, by monotypy. 



Description: Carapace suboblong, rounded behind, and with the 

 dorsal surface usually depressed, not markedly constricted behind the 

 prominent anterolateral angles, the lateral branchial spines small and not 

 prominent. Preocular spine prominent, acute. Spines of rostrum united at 

 base, acute and but little divergent. Eyes small, mobile, but not com- 

 pletely retractile. Basal antennal [article] narrowing slightly from the 

 base to the unarmed distal extremity ; flagellum exposed and visible from 

 above at the side of the rostrum. Merus of the [external] maxillipeds 

 truncated at the distal extremity and but slightly notched at the antero- 

 internal angle, [there] articulated with the next [segment]. Chelipeds 

 in the adult male well developed ; palm compressed, but slightly turgid 

 in the middle, and often slightly carinated above; fingers acute, and 

 having between them, when closed, an interspace at the base. Am- 

 bulatory legs short, with the [propodal] segment more or less dilated 



