224 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv.. 



and an av^erage depth of 1 foot. It flow.s with a .stead}' current and is 

 known to be a part of Echo River. 



All the specimens upon which this paper is based have been depos- 

 ited in the United States National Museum. 



Suborder AMPHIPODA. 



Family GAMMA RID.E. 



GAMMARUS PROPINQUUS, new species. 



fyjj^^—]^o. 25545, U.S.N.M. Collected by W. P. Hay, August 

 28, 1901, from a spring- about 2 miles north of Manunoth Cave, Ken- 

 tucky, 



DeHi-rlptJtm. — Similar to Gaiiuiiai'ux fa.sciati(-'< Say. but with the 

 following- characters : 



First pair of antennae less than half as long as the body, the Hagellum 

 with about twenty-live segments, the accessory branch nmch shorter 

 than either segment of the peduncle and composed of but two or three 

 segments. 



Second antennte from half to three-fourths as long as the first; the 

 second and third basal segments of about equal length; the Hagellum 

 slightly longer than either segment and composed of twelve articles. 



First pair of gnathopoda with the inferior margin of the carpus and 

 hand rather densely fringed with hairs, the longest of which are equal 

 to the width of the carpus; hand with the palmar surface very oblique, 

 hardly distinguished from the inferior surface, armed with a few long 

 bristles and short teeth; dactyl much curved. 



Second pair of gnathopoda larger, stronger, the palmar surface less 

 oblique, being at an angle of about 50 degrees with the inferior surface; 

 carpus and hand fringed with hairs as in the preceding appendage; 

 dactyl stronger and straight. 



Basal segments of the last three pairs of pereiopoda lamellar as usual, 

 but with the posterior margin entire and almost unarmed; the succeed- 

 ing segments more or less armed with hairs and short spines, but nowhere 

 excessivel}'. 



Eye elongate, reniform. 



Fifth and sixth abdominal segments with median and lateral groups 

 of spines on their posterior margins. Seventh segment with a few 

 scattered spines, apparently not arranged in groups, along the posterior 

 margin. 



Telson cleft to its base; each division with the distal extremity armed 

 with a tran verse row of slender spines; outer margin with two rather 

 slender spines. 



Rentarl'ti. — This species, which appears to be distinct from any 

 hitherto described, was found in small numbers in several localities in 

 the region about Mammoth Cave. The best specimens were obtained 



