IflOPODS OF NORTH AMEKICA. 



423 



jn.st below the anterior lobe. The sixth and seNcnth seg'inents liave the 

 l)().steri()r part of the lateral margin excavate, the anterior part pro- 

 jeeting in a lar^e lol)e, and the epiinera laro-e and conspicuous and pos- 

 teriorly situated just l)elow the middle of t\w lateral maro-jn. 



The abdomen is composed of tAvo shoit s(>o-ments followed by a laro-e 

 t( rminal seonient, which has a 



/•C;!^^# 



Fk;. }76. — AsELns intermedus (After Forbes). 

 ((, One of first fair of genital plates of 

 MALE. X 51. b. One of second pair of <;exital 

 plates of male. X 51. 



laro-e rounded median lobe on 

 the posterior margin between 

 the uropoda. The uro])oda are 

 as long- as the terminal abdom- 

 inal segment. The outer branch 

 is as long as the peduncle. The 

 inner branch is one and one- 

 t hi rd times longei- than the outer 

 bi'anch. 



The first pair of legs are sub- 

 chelate, and have the propodus 

 armed on the inferior margin 

 with a triangular process atxnit 

 the middle, and below this a strong conspicuous spine. The inferior 

 margin of the dactylus is furnished with a row of numerous short 

 spines. All the other pairs of legs are ambulatory. 



The types of this species from which the above description is made 

 were sent to me from the JNIuseum of Comparative Zoology of Har- 

 vard University. 



Specimens collectcKl in the Potomac River near Wasnington of the 

 same or perhaps a closely related species differ only in their larger 

 size, being 4 mm. : 11 mm. ; in having three more articles in the tlagel- 

 lum of the hrst antennae, the flagellum of the second antenna^ having 

 also a larger number of articles, sixty-three altogether, and in having 

 the uropoda ecjual to two-thirds the length of the terminal segment. 



ASELLUS BREVICAUDA Forbes. 



Axelhis bi'eviainda Formes, Bull. 111. Museum Nat. Hiat., No. 1, 1876, pp. 8-10. — 

 rNDERWooo, Bull. 111. State Lab. Nat. Hist., II, 1886, p. 359.— Richakdsox, 

 Aiuericau Naturalist, NXXIV, 1900, p. 297. 



Localities. — Found in clear, rocky rills in ,Iackson and Union coun- 

 ties, in southern Illinois; small creek emptying into Kedfoot Lake, 

 Tennessee. 



Body oblong-ovate, three times longer than wide, 4 mm.il!:^ mm. 



Head more than twice as wide as long, 1 mm. :2i nun., with the 

 anterior margin excavate and the antero-lateral angles somewhat 

 truncate. The eyes are small, round, composite, and situated at the 



