28 U.S. NATIONAL MUSEUM BULLETIN 259 



with about 6 marginal setae. Pereopod 6 about equal in length to 

 pereopod 7 but with more slender segments and more proximally 

 expanded basis. Fifth pereopod 75 to 80 percent as long as pereopods 

 6 and 7, distoposterior lobe more distinct. Dactyls of pereopods 5-7 

 about 1/3 as long as corresponding propods. Median sternal, pleonite 

 sternal and 7th coxal gills absent; bifurcate sternal gills relatively 

 small. 



Abdominal side plates: posterior margins shghtly convex to nearly 

 straight, with 1 to 3 setae each; posterior corners of plates 1 and 3 

 rather blunt and poorly developed, that of plate 2 more rounded; 

 ventral margin of 2nd plate with 2 spines, that of 3rd plate with 4 

 spines. Pleopod 1, inner ramus a little longer than peduncle. Uropod 

 1 with up to 30 spines; inner and outer rami about equal in length, 

 approximately 2/3 length of peduncle, Uropod 2 with up to 21 

 spines; outer ramus about equal m length to peduncle but a little 

 shorter than inner ramus. Uropod 3, ramus about 50 percent as 

 long as peduncle and armed apicaUy with 3 unequal spines. Telson 

 subrectangular, about 2/3 as broad as long, apical margin convex and 

 armed with about 15 spines. 



Type locality. — Witheros Cave, Bath Co., Va. The type locaUty 

 is a medium-sized, maze cave with a small stream system in the lower 

 level. This cave is developed in an isolated band of massive, Helder- 

 berg limestone (Devonian age) which crops out in eastern Bath Co. 

 At least part of the type series was taken from a small, gravel-bottom 

 stream in the eastern section of the cave. 



Distribution and ecology. — Only one other record exists outside 

 of the type locality. A single female was collected from a tributary 

 to the Cow Pasture River in June, 1960 (cf.. Material examined). 

 This site is roughly 20 miles southwest of Witheros Cave but in the 

 same drainage system. This single epigean record is undoubtedly 

 the result of the animal having been washed out of a subterranean 

 habitat. Collections of S. mundus from the type locality have been 

 made at two different sites in the cave, and both collections contained 

 specimens of S. morrisoni (see below). The ratio of abundance of 

 the latter to the former was 14:3. 



Stygonectes morrisoni, new species 



Figure 4 



Material examined 



VIRGINIA. — Bath Co.: Witheros Cave, female holotype, male allotype, and 13 

 paratypes, J. P. E. Morrison, Mar. 22 and 23, 1941 (USNM). 



Diagnosis. — Generally distinguished from other species of the 

 emarginatus group by relatively small size, small to rudimentary inner 



