656 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



Dredged in Lake Superior, in company with Gammarus limnceusy 

 among Cladoj^liora, in eight to thirteen fathoms, on the south side of 

 Saint Ignace Island. 



The incubatory lamell.ie of the female are very large, projecting much 

 beyond the epimera of the anterior legs, as in C. recurvatus Grube, 

 (Archiv fiir [tfaturgeschichte, vol. xxxii, p. 410, i)l. 10, fig. 1,) which our 

 species much resembles in the form of the antennulne, antennae, anterior 

 legs, &c., while it differs much in the j)Osterior caudal stylets and in the 

 form of the telson. 



A single specimen of a male Crangonyx, collected by Mr. J. W. Milner 

 n an estuary of Lake Huron, belongs apparently to this species, but is 

 very much larger, being 14"™ in length, so that it is quite probable 

 that the specimens from Lake Superior are all young. This large spec- 

 imen, however, agrees in all essential features with the smaller ones. 



Crangonyx vitkeus Packard. 



11 Stygoh-omus vitreus Cope, Americau Naturalist, vol. vi. p. 422, 1872; Third aud 

 Fourth Annual Reports of the Geological Survey of Indiana, p. 181, 1872. 



Crangomjx vitreiis Packard, Fifth Annual Report of the Peabody Academy of 

 Science, Salem, p. 95, 1873. 



Dr. Packard's specimens were from three different wells in Orleans, 

 Ind., and were collected by M. N. Elrod, who says that many of them 

 were in and on buckets that had been iu the bottom of the well for sev- 

 eral days. Professor Cope's specimens were from Mammoth Cave, Ken- 

 tucky, but are described in such an unintelligible manner that it is very 

 doubtful whether they belong to the same species, or even genus, as Dr. 

 Packard's specimens. I have, however, followed Dr. Packard in quoting- 

 Professor Cope's name as a synonym. 



Ceangonyx tenuis, sp. nov. 



A slender, elongated species, with very low epimera, resembling more 

 in form the species of Niiihagus than the typical species of Grangonyx. 



Eyes not observable in alcoholic specimens. Secondary flagellum 

 of the antenulf© very small, composed of two segments, of which the 

 terminal is very short. 



First aud second pairs of legs differing but little iu the two sexes. 

 First pair stouter than the second, aud with the palmary margin of the 

 propodus much more oblique; the palmary margin of the propodus of 

 both pairs, aud in both sexes, armed each side with a series of stout, 

 obtuse spines, with a notch aud a cilium near the tip. 



First three segments of the abdomen longer than the last three of the 

 thorax ; fourth, fifth, and sixth together scarcely longer than the third. 

 Caudal stylets all extending to about the same point. First pair with 

 the rami subequal, scarcely half as long as the peduncle. Peduncle iu 

 the second pair reaching a little beyond the peduncle of the first pair ; the 

 rami very unequal, the outer only half as long as the inner. Posterior 

 pair scarcely as long as the telson ; the single terminal segment very 



