MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 39 



will extract the following remarks as to its specific character and affinities from the first mono- 

 grapher of the genus, Dr. Hagen: 



The shape of the rostrum is somewhat analogous to that of C. afflnis; the margius are more parallel at the base. 

 The lamina of the anteuuro is long, but strongly dilated nearer to the tip; the epistoma is shorter aud broader than 

 iu the other species; the basal joint of the inner antenna} has a spiue at the tip which in the other species is always 

 nearer to the base. The fore border of the cepbalothorax is not angulated behind the antennas, as in all other species. 

 Nevertheless the number of the hooked legs, the form of the abdominal legs, aud the elongated body and hands, exclude 

 C. pellucidus from the other groups. Some, no doubt, will prefer to regard C. pellucidus as a distinct group or genus, 

 still, as I am convinced, without foundation. The most strikiug differences consist in the aberrations in the shape of 

 the foreparts and of the limbs of the head (pp. 33, 34). 



In speaking of the eyes, Dr. Hagen appears to be in error iu stating that the " optic fibers" 

 are not developed. If reference is here made to the optic nerve, it is, as we shall see further on, 

 well developed, while, as he truly says, the " dark-colored pigments" are not developed. 



The specimens from Wyandotte Cave described by Cope as Orconectes inermis are scarcely a 

 variety of G. pellucidus, as originally stated by us in our paper " On the Cave Fauna of Indiana,"* 

 Professor Faxon also remarks : 



C. pellucidus is subject to considerable variation. In some specimens the rostrum is shorter than in typical 

 specimens, and contracts more from the base to the lateral teeth, which are much less prominent. The spines of the 

 postorbital ridge and sides of the carapace are slightly developed. This is the form described as a new species 

 {Orconectes inermis) from Wyandotte Cave, Indiana, by Professor Cope, in 1872. I owe to Prof. A. S. Papkard an oppor- 

 tunity to examine Cope's type. It is a male, Form II, with the first pair of abdominal appendages not articulated, a 

 condition often found in the second form males of this species. After an examination of this specimen I can indorse 

 the opinion of Hagen (Amer. Naturalist, Aug., 1872), aud Packard (Fifth Ann. Eep. Peab. Acad. Sci. for 1872), ex- 

 pressed before seeing the specimen, that the variation is not of specific value. All the specimens which I have seen 

 from the Indiana caves, amounting to six in number, belong to this form. But the same form also comes from the 

 Mammoth and neighboring caves in Kentucky. Iu a gigantic female in the Museum of Comparative Zoology (No. 

 3417, collected in Mammoth Cave by F. W. Putnam) the peculiarities of Cope's form are intensified. The point of 

 the rostrum does not reach the distal end of the peduncle of the autennule, and hardly attains the proximal end of 

 the distal segment of the peduncle of the antenna.t The lateral rostral spines are reduced to salient angles. The 

 postorbital ridges are destitute of spines, as in C. barton.it. The autenual scales reach but to the proximal end of the 

 terminal segment of the peduncle of the antenna. The lateral spinules of the carapace are represented by granular 

 tubercles. The spines of the meros of the cheliped are short aud tooth-like, those on the upper surface are blunt, 

 those beneath are irregularly disposed, without the clear biserial order seen in the typical form, and also in Cope's 

 type of 0. inermis. The hands are broad, flattened, and tuberculate. 



This species is more widely diffused throughout the cavernous region of Kentucky and Indiana 

 than is generally supposed. 



A male collected by us from Bradford Cave, Indiana, does not differ from a male from Mam- 

 moth Cave. 



In a male from one of the Indiana caves (which cave is not indicated) the cephalothoracic 

 suture is much more acutely produced posteriorly than in a male from Mammoth Cave. 



In the male the rostrum is narrower and its spines, both frontal and lateral, are longer and 

 slenderer than in the female. 



Comparing two males of the same form from Mammoth and Wyandotte caves, the former has 

 the right hand the larger, and the Wyandotte one the left hand the larger. Although the Wyan- 

 dotte male is a little the smaller, the large baud is about one-fourth larger and is broader than in the 

 Mammoth Cave one. The rostrum of the Mammoth Cave example is broader and the sides less raised 

 and thickened. In the Mammoth Cave specimen the inner edge of the end of the antennal scale 

 reaches as far as the lateral spines of the rostrum; in the Wyandotte male the scale reaches far be- 

 yond the lateral spines, more than half way between the lateral spine and the end of the median spine. 

 These Iregard as simply individual differences, as in another male from Wyandotte or Bradford Cave 

 the large hand is of the same relative size and on the same side as the Mammoth Cave male. 



In the females from different caves in Indiana (received from Dr. John Sloan), one has a slightly 

 narrower rostrum than the other, which is a larger individual. 



In a female from Diamond Cave, which we collected, the larger hand is the left one, the rostrum 

 aud antennal scale are shorter than iu a large female from Mammoth Cave; otherwise it does not 

 differ essentially. 



* Fifrh Rep. Peab. Acad. Sci., Salem, 94, 1*873. 



t In the typical form of C. pellucidus the rostrum equals or exceeds iu length the peduncle of tbo antenna. 



