FRESH-WATER CRUSTACEA OF THE UNITED STATES. 641 



with a few slender sette at tip. Telson stout, as long as broad; the pos 

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



Length from front of head to tip of telson, 4'°'".5 to 6'"°^.5. | 



Abundant in pools of stagnant water, IsTew 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, [JsTebraska, by 

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

 tion of 1873 ; in the West Fork of the Des 3Ioines Eiver, Humboldt, 

 Iowa, aud at Salem, Mass., by Mr. Caleb Cooke ; at Grand liapids,, 

 Mich., aud Bangor, Me., by Mr. N. Coleman ; aud at I^orway, Me., by 

 myself. 



Since the above was in the hands of the printer, [ 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 upou 

 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 AmpMthoe aztecus Saussure, (Memoire sur divers Crustaces nou- 

 veaux du Mexique et des Antilles, p. 58, pi. 5, fig. 33, 1858,) from a 

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

 ured from the male alone, has evidently no affinity with Amphithoe m 

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

 Hyalella 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. 



Allorohestes Kiiicl-erhocl'en of Bate, (Catalogue Amphipodus Crustacea 

 British Museum, p. 3G, pi. 6, fig. 1, 18G3,) 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 resi)ects, 

 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 pair have very stout hands 

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

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

 incorrectly) as composed of two segments. 



Family Lysianassid^. 



PoNTOPOKEiA HoYi, sp. nov. (Plate II, fig. 5.) 



Ponioporeia affinis Smith, American Journal of Science, 3tl series, vol. ii, p. 45^,, 



1871 ; and Preliminary Report on Dredging in Lake Superior, p. 1022, 1^*71. 

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

 Gammarus irevistijlis Stimpsou, 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 



