48 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



individuals become long-limbed and blind. There is apparently no struggle for existence, but the 

 direct influence of darkness, united with heredity, are plainly the immediate agencies in the trans- 

 formation. 



Family PHALANGIDiE. 



Phalangodes robust a Simon. 



Plate XIV, figs. 2, 2a, 26. 



iii, 164, 1877. 



Scotolemon robustum Pack. Bull. Hayden's U. S. Geol. Surv. Terr. 

 Phalangodes robusta Simon, Araclinides de France, 150, 1879. 



This species is here referred to at length, because it is the ooly out-of- door species of the 

 genus yet known in the West; and by reference to the figures and description it will be seen 

 how much the cave forms differ from it. 



Eight females?. Tegument deep reddish, with the hinder segments finely bordered with 

 brown; tarsal joints paler, with dense blackish specks; cephalothorax a little paler red, marbled 



with reticulated darker lines. Body pyriform, two-thirds as 

 long as broad; cephalothorax a little more than half as long 

 as wide, the front edge slightly rounded, with the angles well 

 marked. The eye-tuberele not so large and high as in 8. terri- 

 cola Simon, being of moderate size. Eyes black and large, fully 

 developed, while those of 8. terricola are nearly obsolete. 

 Abdomen a little longer than broad; the first five segments 

 well marked, the sutures being much more distinct than in 

 8. terricola or probably any other European species, judging 

 by Simon's drawings. The last three segments, with the 

 outer edge of each segment, free, not united with each other, 

 as are the five basal joints; last segment with the ventral 

 slightly projecting beyond the tergal portion. Beneath are 

 seven well marked sterna, the first and second being united 

 without suture. 



Chelicerse of the usual form, rather stout at base of first 

 joint, but much as in 8. terricola; second joint moderately 

 long; hand of the usual form, a little unequal. Pedipalps 

 unusually short and thick, much more so than in 8. terricola or any other species described by 

 Simon; basal joint broader than long, with a pair of stout, sharp spines and four small ones; 

 second joint nearly two thirds as broad as long, full and swollen above, beneath with four large 

 spines ; third joint much slenderer, one half as long as the second; fourth joint nearly twice as 

 long as broad, with five stout spines, of which the fourth is much larger than the others, the fifth 

 minute; fifth joint as long as, but slenderer than the fourth, with five stout spines, the fifth and 

 terminal spine much larger than the others, and as long as the joint is wide. This joint is a little 

 hairy, while the others are nearly naked. 



Legs stout, much more so than usual in the genus ; anterior pair with three tubercles ending 

 in hairs on the second joint; a larger tubercle on the fourth joint; the three other pairs are 

 unarmed. Second pair of legs longer than the first by one-third of their length. The second and 

 fourth pairs are of nearly equal length, the fourth pair differing in haviug the third joint consid- 

 erably swollen; the third and first pairs of the same length. On the coxae of the second pair of 

 legs is a pair of stout conical spines, meeting over the median line of the body. The anterior 

 tarsi are three-jointed, as in 8. terricola of Europe, the middle one much shorter than the other 

 two, which are of equal length ; those of the second pair five-jointed; those of the third and fourth 

 pairs four-jointed, the ends of the tibiae being constituted so that the limbs appear as if they had 

 five tarsal joints. Ungues rather long and moderately curved. The legs are stouter and shorter* 

 than in 8. terricola, and none of my specimens have the long, singular, sinuate appendage on the 

 first joint present in 8. terricola. (They are not referred to by M. Simon in his description, though 

 my specimens were received from him.) 



Length of body, exclusive of the mandibles, 3.5 mm ; breadth, 2.5 mm . 



Fig 



13. — Phalangodes robusta Pack., (enlarged). 

 a, pedipalp ; b, c, chelicera. 



