226 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Breeding: Ovigerous females were encountered by the Velero III in 

 Peru in January, when 5 of 14 females taken at Lobos de Afuera Island 

 were in berry, and by Schmitt in October, when 17 of 20 females taken 

 at Paita were found gravid. Other records for egg bearing females are 

 from San Benedicto Island, Revilla Gigedo Islands, in April by E. Y. 

 Dawson, from Acapulco, Mexico, in February and September, Dawson 

 and Hubbs, collectors, from the southern part of the Gulf of California 

 in December, E. Y. Dawson, collector, and from Nicaragua in January 

 and Costa Rica in February (Crane, 1947, p. 71). 



Remarks: The material at hand shows considerable variation, both 

 as to presence or absence of tufts of hair on the carapace and the angle 

 of the hepatic lobe, whether acute or obtuse. In fully two-thirds of the 

 Peruvian specimens the carapace is smooth and bare regardless of age 

 or sex, while the remaining third show the gastric pair of tufted tubercles 

 only. Among specimens from Acapulco, Mexico, one small individual 

 has the full complement of tufts (3 gastric, 1 cardiac, 1 intestinal), 

 while of four ovigerous females two are bare and two have the gastric 

 tufts only. The angle of the hepatic lobe seems to be related to sex, 

 most males having an acutely angled lobe, while most females, in keep- 

 ing with their more rotund carapace, have an obtusely angled, or arching 

 lobe. Small males (8 mm) resemble the females in this respect, and males 

 of intermediate size may be quite squarish in appearance. 



The series examined, while less extensive in range than that seen 

 by Rathbun (1925, p. 143 f.), which included a specimen from Chile, 

 is the most extensive available covering material from Lower California 

 to Peru. The specimen from Santa Maria Bay extends the range north- 

 ward along the west coast of Lower California. The specimens from 

 Maria Magdalena Island and from Acapulco bridge the gap between 

 Cape San Lucas and Nicaragua, where the species was collected by the 

 Zaca (Crane, 1947). The absence of Acanthonyx petiveri from the Gulf 

 of California north of La Paz suggests that it is not able to compete 

 with the endemic Epialtus minimus, a prolific species occupying a similar 

 ecological niche. 



The male first pleopod of an Atlantic specimen from Velero III 

 station A46-39 was examined and found to be identical with that of the 

 Pacific form. 



