SUBTERRANEAN AMPHIPOD STYGONECTES 35 



Gnathopod 1 : propod palmar margin long, convex, armed with a 

 double row of about 15 rather irregular-sized spine teeth; posterior 

 angle with 2 large spines, 3 or 4 smaller spines and 2 setae on outside, 

 7 small spines on inside; posterior margin convex, distally with 2 or 

 3 sets of setae, proximally without setae; superior lateral setae m 2 

 sets, inferior lateral setae doubly inserted; naU of dactyl very short; 

 segment 5 with 2 rastellate setae on posterior margin. Gnathopod 2: 

 propod palmar margin convex, armed with a double row of about 

 18 irregular sized spine teeth; posterior angle with 1 large spine, 2 

 smaller spines and several long setae on outside, 7 smaller spines on 

 inside; posterior margin with 4 sets of setae on outside edge, 1 set of 

 3 small setae on inside edge; superior lateral setae triply and doubly 

 inserted, inferior lateral setae mostly doubly inserted; dactyl claw 

 very short; segment 5 with 3 rastellate setae on posterior margin; 

 coxal plate with 8 marginal setae. Coxal plates of pereopods 3 and 4 

 with 11 marginal setae each. Pereopod 7 between 55 and 60 percent 

 as long as body, about equal in length to pereopod 6 and 30 percent 

 longer than pereopod 5. Bases of pereopods 5-7 not broadly ex- 

 panded, about as broad distally as proximally; posterior margins 

 moderately convex; distoposterior lobes distinct but not much pro- 

 duced ventrally. Dactyl of pereopod 5 about 1/3 as long as corre- 

 sponding propod; those of pereopods 6 and 7 about 1/4 as long as 

 corresponding propods. Sternal gills absent on 1st pleonite; coxal 

 gills large. 



Abdominal side plates: posterior margins with 1 setae each, gently 

 rounded and incurving to small, well-defined, subacute corners; 

 ventral margin of plate 2 with 4 spines, that of 3 with 2 spines. Pleo- 

 pod 1, inner ramus about 30 percent longer than peduncle. Uropod 1: 

 outer ramus equal in length to inner ramus, with 13 spines; inner 

 ramus with 13 spines; peduncle without distal process, armed with 

 18 spines. Uropod 2: outer ramus about equal to inner ramus in 

 length, about 80 percent as long as peduncle, armed with 10 spines; 

 inner ramus with 13 spines; peduncle with 8 spines. Uropod 3, 

 outer ramus about 40 percent as long as peduncle, armed apically 

 with 4 or 5 spines. Telson subrectangular, about 25 percent longer 

 than broad; apical margin with shallow excavation, armed on either 

 lobe with 8 to 10 rather slender, unequal spines. 



Type locality. — Millers Cave, about 7/8 mile east of Rockspring, 

 Centre Co., Pa. Access to the type locality is through a sink hole 

 which receives runoff from the surface during wet weather. Millers 

 Cave is developed in Ordovician limestone, which crops out m the 

 Appalachian Valley floor just west of Tussey Mountahi. The single 

 male was taken from a long, shallow, mud-bottom pool some distance 

 from a small stream which flows through the lower level. Although 



