No. 1746. 



I NEW WII'IIII'OI) FROM VIRGINIA— EMBODY 



301 



acutely serrated along the posterior edges, forming great teeth in 

 nearly all cases twice as long as the spines between them (fig. 5). 



Pleopods with their outer rami slightly shorter than the inner. 



Uropods one and two have equal rami; third, with inner ramus 

 rudimentary and very short, about one-third as long as peduncle 

 (fig. 6); outer ramus uniarticulate, with three or four groups of 

 spines on lateral margins and one group of two or three at the distal 

 end. First pair of uropods extending backwards slightly beyond the 

 second which in turn reaches to or slightly beyond the third. 



Telson (fig. 7) longer than broad, longer than the 

 peduncle of third uropod and with an ernargination 

 extending from slightly more than one-half to nearly t w < >- 

 thirds of the distance to base (see table), armed distally 

 with three or four spines on each 

 lobe and on the dorsal surface with 

 three or four spines which seem to be 

 definitely located within the mid- 

 region. 



The postero-lateral angles of the 

 first three abdominal segments are 

 produced backward, each into a 

 tooth and provided with about five 

 or six spines just above the ventral 

 margin. 



Size. — The largest specimen ex- 

 amined was a female with eggs and 

 measured 14.5 mm. in length; the 

 smallest adult, a male measuring 7.0 

 mm . 



Eggs. — The average dimensions of 

 six from different individuals were 

 0.39 by 0.485 mm. 



Type-specimen. — Cat. No. 51290, U.S.N.M. 



This species resembles Eucrangonyx gracilis^ but differences exist in 

 the telson, basal joints of the third to fifth perseopods, in the gnatho- 

 pods, and in the size of the eggs. 



The telson of E. gracilis is as broad as long (see table), not longer 

 than peduncle of third uropod and cleft one-third to one-half the dis- 

 tance to base/ 1 In E. serratus it is longer than broad, longer than 



I'll.,-. 5-7. — E. SERRATCS. PERjEOPOD 5, X 11 



i'iam ; 6, ukopod :s. X 32 diam.; 7, telson, 



X 32 DIAM* 



a Early in the work variations in the depth of the emargination of the telson in 

 Eucrangonyx gracil is wore noted which had do1 been accounted for in the descriptions 

 of that species given in. the works cited in footnote ona previous page. Inordertosee 

 just how far these variations had progressed, a number of specimens were collected 



from a trout brook near Auburn, New York, from Cayuga Lake at Ithaca, Now York, 

 and from a sphagnum bog at McLean, New York. The more conspicuous variations 

 are recorded in the table of measurements on page 305. 



