38 MBMOIES OP THE NATIONAL ACADEMY OF SCIENCES. 



flagellum is usually a little shorter. The propodns of the first pair of feet is similar in outline, but 

 the palmar margin and dactyl are shorter, and the posterior margin longer. The second pair is 

 extremely like the second of the male, but is decidedly smaller than the first. The telson affords 

 a difference so remarkable, that the two sexes, at first sight, would hardly be referred to the same 

 genus. In the female this is very similar to the telson of C. gracilis Smith. It is flattened and 

 slightly emarginate, a little longer than broad, extending to the tips of the second pair of anal 

 legs, and bears two terminal clusters of spines of four or five each. 



This species was first discovered by me in a well at Normal, Illinois, during the summer of 

 1875. It was subsequently found by Mr. Harry Garman in great numbers in springs, and even 

 at the mouths of drains, after a long period of heavy rains. With the advent of dry weather it 

 entirely disappeared from these, but still occurs sparingly in wells. (S. A. Forbes.) 



Ckangonyx lttcifugus Hay. 



Crangonyx luoifugus Hay, Amer. Naturalist, xvi., 144-5. 1882. 



The following description is copied from Mr. Hay : 



This is a small, rather elongated species, that was obtained from a well in Abingdon, Knox county, Illinois. As 

 befits its subterranean mode of life, it is blind, and of a pale color. In length the largest specimens measure about 6 mm . 



Male. — Antennulse scarcely one-half as long as the body. The third segment of the peduncle two-thirds as long- 

 as the second ; this, two-thirds the length of the first. Flagellum consisting of about 14 segments. The secondary 

 flagellum very short, and with but 2 segments. Antennse short, only half as long as the antennulse. Last 2 segments 

 of its peduncle elongated. Flagellum consisting of but about 5 segments, and shorter than the last two segments of 

 the peduncle taken together. 



Second pair of thoracic legs stouter than the first. Propodite of first pair quadrate, with nearly a right angle 

 between the palmar and posterior margins. Palmar surface on each side of the cutting edge, with a row of about 6 

 notched and ciliated spines, one or two of which at the posterior angle are larger than the others. The cutting et'.ge 

 is entire. Dactylopodite as long as the palmar margin, and furnished along the concave edge with a few hairs. 



Propodite of the second pair of legs ovate in outline, twice as long as broad. The palmar margin curving grad- 

 ually into the posterior margin. The cutting edge of the palmar surface uneven, and having, near the insertion of 

 the dactyl, a square projection. The palmar surface also armed with two rows of notched and ciliated spines, five 

 in the inuer row, seven in the outer. Dactyl short and stout. 



Two posterior pairs of thoracic legs longest of all and about equal to each other. All the legs are stout and 

 their basal segments squamiform. 



Postero-lateral angle of first abdominal segment rounded; of second and third, from obtuse-angled to right-angled. 



First pair of caudal stylets extending a little farther back than the second; these slightly exceeding the third. 

 The peduncle of the first pair somewhat curved, with the concavity above, the rami equal and two-thirds as long as 

 the peduncle. The peduncle of the second pair little longer than the outer ramus. Inner ramus nearly twice as long 

 as the outer. Third pair of caudal stylets rudimentary, consisting of but a single segment. This somewhat longer 

 than the telson, broadly ovate, two-thirds as broad as long, and furnished at the tip with two short spines. 



Telson a little longer than wide, narrowing a little to the truncated tip, which is provided at each postero- 

 lateral angle with a couple of stout spines. 



Female. — In the female the propodite of the anterior pair of feet resembles closely that of the corresponding 

 foot of the male. The palmar margin of the second propodite is less oblique than in the second foot of the male, and 

 does not pass so gradually into the posterior margin. It is also destitute of the jagged edge and the square process 

 of the male foot. There are fewer spines along the margin. O ne of the spines at the posterior angle is very long 

 and stout. 



This species appears to resemble C. tenuis Smith, but is evidently different. In that species, as described by 

 Prof. S. I. Smith, the first pair of feet is stouter than the second, and has the palmar margin of the propodite much 

 more oblique. The reverse is true of the species I describe. Nor do I understand from the description of C. temtis 

 that the posterior caudal stylets each consist of a single segment. There are some minor differences. From C. vitreus, 

 judging from Professor Cope's description in American Naturalist, volume vi., page 422, it must differ in the caudai 

 stylets. " Penultimate segment with a stout limb, with two equal styles," is a statement that will not apply to my 

 species, whichever the "penultimate" segment may be. 



Cambarus pellucidus (Tellkampf). 



Astacus pellucidus Tellkampf, Arch. f. Anat., Phys. u. Wissensch. Med., 383, 1844. 



Cambarus pellucidus Erichson, Archiv f. Naturgesch., xii, Jahrg. I, 95, 1846. 



Orconectes pellucidus Cope, and Orconectes inermis Cope, Amer. Naturalist, vi, 410, 419, 1872. 



Cambarus pellucidus Smith, Rep. U. S. Com. Fish., 1872 and 1873, 639, 1874. 



Cambarus pellucidus Faxon, Proc. Amer. Acad. Arts and Sci., xx, 139, 1884; revision, 90, 1885. 



Next to the blind-fish of Mammoth and other caves, the blind crayfish first discovered in 1842 

 by Dr. W. T. Craige has, from its size, attracted the most general attention from the public. We 



