FEESH- WATER CRUSTACEA OF THE UNITED STATES. 647 



with a few slender setse at tip. Telson stout, as long as broad; the pes 

 terior margin rounded and famished each side with a slender seta. 



Length from front of head to tip of telson, 4'^™.5 to G'^'^.o.] 



Abundant in pools of stagnant water, New Haven, Conn. Also col- 

 lected at Madison, Wis., by Professor Verrill ; Madeline Island, Lake 

 Superior, by Mr. J. W. Milner ; at The Dalles, Oregon, by Mr. Oscar 

 Harger; and in Lake Eaymond and Birdwood Creek, Nebraska, by 

 Messrs. Oscar Harger and T. M. Prudden, of the Yale College expedi- 

 tion of 1873; in the West Fork of the t)es Moines Eiver, Humboldt, 

 Iowa, and at Salem, Mass., by Mr. Caleb Cooke ; at- Grand Eapids, 

 Mich., and Bangor, INle., by Mr. N. Coleman; and at Norway, Me., by 

 myself. 



Since the above was in the hands of the printer, I have received numer- 

 ous specimens of this species, collected at Lake Okeechobee, Florida, by 

 Dr. Edward Palmer. In some of these specimens, the dorsal teeth upon 

 the first and second segments of the abdomen are very small; and, in a 

 very few specimens, they are wholly, or almost wholly, wanting. 



The AmphitJwe astecus Saussure, (Memoire sur divers Crustaces nou- 

 veaux du Mexique et des Antilles, p. 58, ])\. 5, fig. 33, 18.j8,) from a 

 reservoir at Vera Cruz, Mexico, although very badly described and fig- 

 ured from the male alone, has evidently no affinity with AmphWioe in 

 any modern sense, undoubtedly belongs to this genus, and may be called 

 Syalella azteca. The discovery of the far southern range of our species 

 renders it quite probable that it may prove to be synonymous with this 

 species of Saussure. 



Allorchestes KnickerhocJieri of Bate, (Catalogue Amphipodus Crustacea 

 British Museum, p. 36, pi. 6, fig. 1, 1862,) supposed to have come from 

 the fresh waters of North America, belongs probably to this genus. It 

 has the first and second segments of the abdomen armed dorsally as in 

 our species, which it resembles considerably in several other respects, 

 although the figures and description, indicated as made from the female 

 only, represent the first pair of legs much like those of the second pair of 

 the female of our species, while the second ])air have very stout hands 

 and resemble the second pair of legs of the male of our species. The 

 palpus of the first pair of maxilhie, in Bate's species, is figured (perhaps 

 incorrectly) as composed of two segments. 



Family Lysianassld^. 



PoNTOPOREiA HoYi, sp. nov. (Plate 11, fig. 5.) 



Pontoporeia affinis Smith, American Journal of Science, 3d series, vol. ii, p. 452', 



1871; and Preliminary Report on Dredging in Lake Superior, p. 1022, 1871. 

 Gammarus Hoyi Stimpsou, MSS., (full-grown male form.) 

 Gammarus brevistijUs Stimpson, MSS., (female.) 



On first examining specimens of this species, obtained in Lake Supe- 

 rior in 1871, I regarded them as specifically identical with the Fonto- 

 poreia affinis of the Scandinavian lakes and the Baltic. A subsequent 



