MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 
33 
these species inhabit, they appeared at the surface in springs, and even at the mouths of tile 
drains, in such numbers that a hundred could be taken in an hour. A lew females were observed 
with eggs at this time (July).” 
Upon the whole, the Illinois specimens are the most aberrant, i. e., the farthest removed from 
Asellus communis, of any forms found in Mammoth or other caves. They are more linear than 
some specimens taken from wells in Annville, Lebanon county, Pennsylvania, kindly sent us by 
Mr. L. H. McFadden, who writes me that they also occur in the springs and wells in the limestone 
rocks of Cumberland and York counties. 
The Pennsylvanian examples were large and well developed; the females were 16 mni in length; 
and the greatest width, 4 mm ; length of first antennae, 3 mm ; of second antennae, 15 mm , or almost as 
long as the body itself. The first antennae were large, well developed, and sixteen to seventeen 
jointed. PI. Ill, figs. 4; 4 a represents the end of the antennule, showing three olfactory rods arising 
from the sixth joint from the end, this being probably an anomaly.* 
Ccecidotjea nickajaokensis Packard. PI. Ill, figs. 9, 9a, 
Coecidotcea nicTcajaclcensis Pack., Amer. Naturalist, xv, 879, November, 1881. 
Body longer, narrower, and slenderer than in G. stygia. The antennae are sometimes very 
long, and reach to the end of the third joint of the second antennae; they are sometimes nearly 
twice as long as in G. stygia, and are purplish-white, while the flagellum is provided with long 
hairs. Figs. 9,9a, however, represents a short first antenna composed of 
only 8 to 9 joints with a single long olfactory rod on the sixth joint. 
The second antennae are as long as the head and extend back¬ 
wards as far as the base of the abdomen. The legs are much longer 
and slenderer than in C. stygia. The abdomen is long and narrow, 
and the caudal appendages are moderately long in one specimen and 
short in another; in one individual the outer branch is much shorter 
and smaller than in the others, and in most it is as long as the basal 
joint. On the whole, the caudal appendages are no longer than the 
telson or terminal segment of the abdomen, while in G. stygia they 
are half as long as the entire body. 
This species forms, in the antennae and slightly purplish color 
and the proportions of the leg-joints, perhaps a nearer approach to the 
genus Asellus than that of Mammoth and Wyandotte caves; on the 
other hand, C. stygia approaches Asellus more in its shorter, broader 
body, with the shorter, broader abdomen. It seems quite evident that 
the two species must have descended from different species of Asellus. 
Whether there is an additional species in the Southern States from 
which the present species may have been derived remains to be seen. 
The two specimens from Lost River, found by Dr. Sloan in that 
subterranean abode, were of the normal form and size of A. communis, but bleached as white as 
C. stygia; the eyes are black and distinct. This variety may be called pallida. It is interesting 
to note the occurrence of this bleached variety, which may have become thus modified after but a 
few generations; perhaps but one or two. 
Besides Asellus communis, which is widely diffused throughout the Eastern and Central States, 
Mr. Forbes has described two species which occur in southern Illinois, neither having been 
detected in central or northern Illinois, although the most varied situations were carefully.searched. 
Our sketches (PI. IV, figs. 3, 3a-3g) will give some of the details of structure of A. communis, 
which will serve as a basis of comparison. 
Asellus intermedins Forbes, Bull. Ill. Mus. Nat, Hist., No. 1,10. 
This species, as remarked by its describer, is intermediate between Asellus communis and 
A. brevicauda. As will be seen by reference to Forbes’ Fig. 14, the caudal stylets are like those of 
Fig. 7. — Coecidotcea nickajacTcensis, 
Pack, a, antennule; b, caudal stylets; 
all enlarged. 
* The auditory bristles of this species were mistaken by Mr. Hubbard for 
See his Fig. 10b, and Amer. Ent., iii, p. 80. 
S. Mis. 30, pt. 2-2 
‘an unknown oiliate Infusorian?” 
