APPENDIX F. ARACHN1DIANS. 235 



labrum is comparatively small, whilst the maxillae are stout. The palpi 

 are slender, and composed of five joints. The first joint is very small, 

 inconspicuous ; the second is the longest and the most slender of all ; 

 the third is somewhat larger than the first, the fourth larger than the 

 third, and the fifth larger- than the fourth, which is swollen and sub- 

 concave beneath, provided with two minute hooks inserted upon two 

 tubercles. In the female the palpi are slenderer than in the male, and 

 the last joint is simple and longer than the third. The legs are long 

 and slender, composed of six joints : the hind pair is the longest ; the 

 ^first pair is the next in length ; the third pair is the shortest. The 

 third joint is the smallest in the four pairs ; the first joint is the next in 

 length, and the stoutest ; the second pair is the longest in the three 

 anterior pair ; the fifth comes next, then the fourth and sixth. In the 

 posterior pair the fifth joint is the longest ; then the second ; then the 

 fourth and sixth. The fusi, four in number, are short, intimately 

 grouped, and composed of a single joint. The whole surface of the . 

 body and legs, above and below, is densely covered with short hairs. 



The color above is uniform grayish brown. The abdomen, cephalo- 

 thorax, and first joint of legs beneath, are deep black. The second, 

 third, and fourth joints are of the color of the upper parts upon their 

 middle, and black near their articulations. The fifth and sixth joints 

 are almost entirely black. The extremity of the chelicerae and palpi are 

 black beneath. When the hairy covering is removed, the color is a 

 uniform chestnut-brown. 



The color may present some variations ; thus in the notes of Captain 

 Marcy, one is described as having "the back brown, belly dirty white, 

 head and legs red." 



One specimen preserved in alcohol exhibits a reddish band down the 

 middle of the cephalothorax, and two black vittse, one on each side of 

 the abdomen. The cephalothorax bgneath is reddish ; and on the 

 abdomen there are two elliptical light spots. 



Specimens were collected the 16th of May on the open prairie, between 

 Camps 1 and 2 ; and on the 1 9th of June, on Canadian river, Arkansas. 



Plate XVI, fig. 4, represents the trophi, showing the labrum (1), ihe 

 maxillaa (m), the palpi (p), and chelicerse (c). Fig. 5 exhibits the 

 disposition of the ocelli. 



