48 
MEMOIRS OE 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 PIIALANGIICE. 
Phalang-odes robusta Simon. Plate XIY, figs. 2, 2a, 2b. 
,_ Scotolemon robustum Pack. Bull. Hayden’s U. S. Geol. Surv. Terr., iii, 164, 1877. 
Phalanyodes robusta Simon, Araehnides de France, 15C, 1879. 
This species is here referred to at length, because it is the only 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-tubercle not so large and high as in 8. tern- 
cola Simon, beiug 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 beiug united 
without suture. 
Chelicerse of the usual form, rather stout at base of first 
fig. 13 ' <ealarged) - J oint ) ,mt 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 thau the first by one-third of their length. The second and 
fourth pairs are of nearly equal length, the fourth pair differing in having the third joint consid¬ 
erably swollen; the third and first pairs of the same length. On the cor® of the second pair of 
legs is a pair of stout conical spines, meeting over the median line of tiie body. The anterior 
tarsi are three-jointed, as in 8 . terricola of Europe, the middle one much shorter thau 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 wore received from him.) 
Length of body, exclusive of the mandibles, 3.5 mm ; breadth, 2.5 mm . 
