MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 43 
middle, narrowing in front and behind, and between the chelicerse deeply cleft; a feature unusual 
in the genus. There are no traces of eyes, either of a cornea or pigment spot. The chelicerse are 
rather smaller than usual and separate at base, and more conical, less 
pyriform than usual; the manus is shorter, and the fingers longer than 
usual, both finger and thumb (the fixed finger) are curved, the tips acute, 
and the inner edge denticulate. The pedipalps are as long as the body 
without the chelicerse; they are rather thick, not especially long; the first 
joint is stout and of uniform thickness, as is the second, which is not con¬ 
tracted at the base, being of uniform thickness; it equals in length the 
width of the cephalothorax; the third is three-fourths as long as the 
second, is slightly contracted at the base, subconical in form; the hand 
is thick and heavy, it is about twice as long as the third joint, and the 
fingers are moderately curved. The abdomen is narrow and rather long, 
with the segments well marked. The body (in alcoholic specimens) is 
dull white, while the pedipalps are horn colored, with a reddish tinge. 
Length of body, including the chelicerse, 2 mm . One specimen from the 
New Market Gave, Virginia.* 
Chthonius packardii Hagen. Plate XI, figs. 3,3 a to 3j. 
Chthonius packardi Hagen, Zool. Anzeiger, II Jalirgang, 399. July 28, 1879. 
Chthonius packardi Hagen, Amer. Entomologist, iii, 83. March, 1880. 
Chthonius packardi Hubbard, Amer. Entomologist, iii, 83. March, 1880. 
Body rather long and narrow; thorax rather flat, considerably longer than wide, nearly one- 
fourth, and about (perhaps a little less than) one-half as long as the abdomen; a little broader just 
behind the front edge, and narrowing somewhat on the hinder edge. The abdomen is considerably 
contracted at the base, especially on the second segment; it is rather narrow, less swollen in the 
middle than usual; it consists of ten distinct segments, of which the seventh and eighth are the 
widest. On the thorax is a lateral row of setfe, five on each side and two in front, but none in 
the center, and two behind. In the young there are four in front. On each side of the abdomen 
are two rows of setae, of the same length as those on the thorax. There are no traces of eyes in 
three specimens; in a fourth rudimentary ones exist. General color (in alcohol) pale horn, with a 
reddish tint; body and legs of the same tint; the chelicerse of the same tint, but the hand of a 
little deeper tint, while the pedipalps are decidedly deeper in color than the rest of the appendages 
and body ; beneath not paler than the upper side of the body. 
Chelicerse (mandibles) of moderate size, full, and swollen towards the base; two-thirds as long 
as the thorax, and about as long as the latter is wide behind the middle; the movable claw or 
finger is shorter than the chelicera is thick, and the fixed thumb is about half as long as the body 
of the chelicerse. On the hand near the base of the finger are two hairs, and the finger itself 
bears two external setse within the middle; on the hand near the division into fingers is a 
group of three straight, stiff, barbed setae (Fig. 3e). On the inside of the middle of the long slender, 
regularly-curved finger are six teeth, f the distal one the largest. The serrula has eighteen 
divisions, the first one free, the distal one very acute. The pedipalps are long and slender, longer 
than the body by nearly the length of their finger. The third joint is about one fourth as long as 
the second; the manus is one-half as thick as long; the fingers are long and slender, nearly but 
not quite as long as the second joint; both are a little curved, with the extreme tips suddenly bent 
in; each finger with a series of fine acute teeth on the inner edge, which end in short set®. The 
legs long and slender, the posterior pair about twice as long as the abdomen; the two posterior 
trochanters twice as large as those of the second pair of legs, and the latter much larger than 
* Chelifer cancroides L.—This species occurred in company with Chthonius packardii in Salt Cave in partial day¬ 
light, 50 to 100 feet from the entrance. This is a cosmopolitan species, being found everywhere in Europe and in the 
Atlantic as well as Pacific States. This is its first occurrence in caves ; but its appearance in a single cave, may for 
the present, at least be regarded as accidental. 
t These hairs form the so-called organs of smell of Stecker. (See Hagen, Zool. Anzeiger, July 28, 1878, p. 400.) 
Fig. 11 .—Obisium cavicola Pack.; 
enlarged. 
