APPENDIX F. ARACHNIDIANS. 233 



AMCHNTOIANS. 



BY CHARLES GIRAED. 



I. ARANEIDJE. 



1. Mygale hentzii, Girard. 



Zoology, PI. XVT, 1-3. 



Spec. char. — Blackish brown; densely studded with hairs. Cepha- 

 lothorax sub-circular, with a median and transversely elliptical infundibu- 

 lurn upon its posterior half, whence shallow grooves radiate towards the 

 periphery. Abdomen ovoid. Palpi composed of five joints besides .the 

 maxillse, a hook in the male. Legs six-jointed. 



Description. — This species is one of the largest of the genus hitherto 

 found within the limits of the United States. The specimen figured, 

 however, is much below the usual size. The cephalothorax is subcir- 

 cular in shape, a little broader in' the male than in the female. The 

 eyes are disposed as in -fig. 3, on a little eminence near the anterior 

 margin, and upon the midial line. On the posterior half of the same 

 region, on a line with the eyes, is a transverse infunclibulum, some- 

 times subcrescentic, convex posteriorly. Shallow and sometimes irregu- 

 lar grooves radiate from that centre towards the margin of the cephalo- 

 thorax. The abdomen is ovoid ; considerably larger in the female than 

 in the male. The labrum is quite small. The chelicerse are robust, 

 regularly arched, terminated by a rather slender .hook, similarly curved, 

 and movable upon the chelicerse. The palpi are six-jointed ; the basal 

 joint, functioning as maxilla, is robust, and not otherwise distinguished 

 from the following, except that it is provided along its inner margin 

 with a brush-] ike series of hairs. The second joint is very short 

 the third is the longest ; the fourth is a little larger than the second 

 the fifth a. little shorter than the third ; the fourth shorter than the fifth 

 the sixth is the size of the second, but differently shaped, being rounded 

 at its extremity, at the inferior surface of which exists a hook, very stout 

 at the base, tapering into an acute point curved downwards and out- 

 wards. In the female the sixth joint of the palpi is as long and of the 

 same shape as the fifth, and deprived of the hook. The fourth pair of 

 legs is the longest ; the first pair comes next ; the second pair is the 

 smallest. They are all six jointed, the first joint short and robust. 



