44 MEMOIBS OF THE NATIONAL ACADEMY OF SCIENCES. 



those of the first pair of trochanters; the terminal tarsal joints of first and fourth legs of nearly 

 the same length, and quite setose, with scattered longer stiff setae, each with a pair of slender 

 curved hooks and a slender curved anchor-shaped plan tula with a thin cylindrical shank. 



Length 2.5 to 3 3 mffi . 



Labyrinth of Mammoth Cave, under stones and fungus (Oozonium), three specimens; and 

 another from the same cave in total darkness; also Dixon's Cave (Packard and Sanborn). One 

 specimen with rudimentary eyes occurred in Salt Cave, 50 to 100 feet in from the mouth, in partial 

 daylight. 



Of the four specimeus from the Labyrinth three are totally blind, with no traces of eyes; the 

 fourth one, of which the exact locality in the cave is unknown, has rudimentary eyes; the cornea 

 could not be detected, and the presence of the eye was only indicated by a silvery- white pigment- 

 spot situated on each angle of the front edge of the thorax, in front of the lateral seta3. One 

 specimen from the New Wyandotte Cave, Indiana, was totally blind, with no trace of cornea or 

 pigment-spot, and the body was white. 



Our specimens agree with Hageu's description in the American Entomologist. My description 

 is drawn up from males. His type-specimens were from Wyandotte Cave. Dr. Hageu's Kentucky 

 specimens were from the bottom of the Dome, Mammoth Cave, "with dead bat," November 9, and 

 Long Cave, near Glasgow Juuctiou, Kentucky, 1 mile from daylight, May 11. Hagen writes as 

 follows of the Mammoth Cave form with two eyes : 



It is pale yellowish ; the thorax, mandibles, palpi, legs, and segments of the abdomen about the same color ; the 

 base of the mandibles a little darker; the abdomen bet ween the segments and on the sides paler. I have seen only 

 three specimens in alcohol, all from the Mammoth C ave region, one couple from one locality and a female from 

 another locality. I have compared all very carefully with C. (Blothrus) packardi, from Indiana. They are a little 

 longer, 3 to 3.2 mm long, but a little darker, or perhaps a little less white, but all three have on each side of the thorax 

 one eye, distant from the anterior border as far as the length of the diameter of the eye. The movable finger of the 

 mandibles is not indented. The examination of all other details shows no difference. 



In his article in Zoologischer Anzeiger, July, 1879, Dr. Hagen refers to this form as follows: 



As the position and number of the eyes has hitherto furnished for (Jhelifer genera a trustworthy indication, j 

 had described it as a new species. * A subsequent very close comparison with (Blothrus) packardi gave as a result 

 that the two species appear to be identical; only the former has' two eyes; the latter is blind. Further research 

 showed that neither can be separated from the genus Chthonius, which has two eyes on each side. Consequently we 

 have here the interesting fact that Chthonius living without the cave have two eyes on either side, aud that within 

 the caves live forms of this genus in which either the anterior pair of eyes is aborted or these two are wanting, aud 

 light-refracting cells (lic'htbrecheude Kerne) under the skin, at the base of the sensitive hairs, seem to form a partial 

 substitute for the wanting organs of sight. 



I append Mr. Hubbard's excellent description of this form. 



Dr. Hagen has, with the greatest liberality, placed at ray disposal his unpublished descriptions and figures of 

 new Pseudoscorpions belonging to the genus Chthonius. The following is the description of the cave species. The 

 few changes I have taken the liberty of making in his manuscript have been rendered necessary by new facts devel- 

 oped in correspondence, and in an article published in advance of the descriptions by Dr. Hagen in the Zoologischer 

 Anzeiger, Leipsig, July, 1879. 



"Chthonius packardi Hagen, n. sp — (Fig. 9, a male, enlarged fifteen times; 6 left mandible from below; c feathered 

 bristle of the mandibles more enlarged ; d movable finger of mandible, occasional in female; e chela of the palpus; / 

 termination of tarsus; g piantula from above.) 'Dull whitish mandibles and palpi very light brown, segments of the 

 abdomen yellowish white. Thorax flat, a little longer than broad, quadrangular; very little enlarged just before the 

 anterior border, and a little narrowed behind in female ; lateral borders nearly straight, a little convex j ust before the 

 anterior border where the eyes should have been ; angles rectangular, the hind ones scarcely rounded ; no eyes ; thorax 

 smooth, with a few sensitive bristles, four on each side, two near the anterior border and two near the posterior one, 

 two more in the middle each side nearer to the anterior border, which is a little produced iu middle; mandibles large, 

 one third shorter than the thorax; base convex above, oblong, a little narrowed to the fingers, which are shorter than 

 the base; the movable finger incurved, strongly pointed, with sometimes a small knob or external indentation before 

 the tip; on the under side of the base, just before the division into fingers, internally, three long feathered bristles 

 placed in a line, usually larger on the left mandible, sometimes wanting (or rubbed off?); abdomen less than twice 

 as long as the thorax, scarcely broader at base, ovoid, thicker in the female ; two rows of hairs on the segments 1 to 

 3, four rows on the three following segments, and six rows on the two following segments ;t a transversal row of 



* Under the manuscript name C. (Blothrus) incertus. 



t The number of hairs is found to vary on the abdomen. ( Hub. ) 



