128 CRUSTACEA. 



ACANTHONYX PETIVERII ? 



Valparaiso, Chili. 



Plate 5, fig. 6 a, hand of male, enlarged four diameters ; b, extre- 

 mity of second pair, enlarged five diameters ; c, extremity of fifth 

 pair, ibid. ; d, abdomen of male. 



The specimens agree with the description of the P&tiverii. It is 

 very near, also, the Mac Leayi of Krauss, but the male has only six 

 segments to the abdomen. The two sides of the carapax are very 

 nearly parallel, and the two posterior teeth of the margin are quite 

 small, although appearing prominent through the setse. The hand 

 of the male is very stout, the breadth being nearly equal to the length 

 from the base to the fingers. The setigerous crest on the carpus of 

 the anterior legs is distinct and prominent. The two setigerous 

 tubercles on the stomach region are wanting. 



The following are measurements of males : Specimen A. Length 

 of carapax, seven lines ; breadth of carapax, four and a half lines ; dis- 

 tance between the first and second lateral teeth, one and three-fourths 

 lines; distance between the second and third, one line. Specimen B. 

 Length of carapax, eleven and one-fourth lines; breadth of carapax, 

 seven lines; distance between first and second lateral teeth, three and 

 one-fourth lines ; distance between second and third, one and one-half 

 lines. 



The tarsus in the eight posterior legs is oblong triangular. In the 

 second pair, the two margins regularly and evenly diverge from the 

 base, and the oblique truncation is very nearly transverse. In the 

 fifth pair, the oblique truncation is more oblique ; but the distance 

 from the angle to the base of the joint is much the greater part of the 

 joint, and the margin inside of this angle, that is, between it and the 

 articulation of the tarsus, is far from parallel to the dorsal margin of 

 the joint. The number of teeth in a row on the inner margin of the 

 tarsus is about fourteen. 



In the male hand, the fingers are a little open, and close entirely 

 only at tip, and the inner margin has seven or eight broad teeth, 



