2'.)r) MliLLKTIiN r)4, I'NITKI) STATES NATIONAL MTTSEUM. 



TIr' biisiil article of the seeoiid uiitcmiie is \-erv short; the seeoiul and 

 third are Ioniser than the first and sul)e([ual; the fourth and fifth are 

 aljoiit equal and each is one and a half times longer than the third. The 

 flagellum is eoniposed of twelve articles. The second antenna? extend 

 a little beyond the posterior margin of the first thoracic segment. The 

 maxilliped has a palp of five articles. The palp of the mandibles is 

 composed of thi-ee articles. The frontal lamina is large and conspicu- 

 ous, and has (he anterior division wide and long, with the post-lateral 

 or ventral angles drawn out, giving it somewhat of a horse-shoe shape. 

 The clypp us is transversely oblong, and fits into the concavity of the 

 posterioi- i)art of the frontal lamina; its posterior margin is fringed 

 with cilia. 



The segments of the thorax, are equal in length. The epimera are 

 not distinct from the segments. The lateral margins are nearly 

 straight. 



The al)domen is composed of two segments. The first segment is 

 about as long as the last thoracic segment and has one suture line on 

 either side. The terminal segment is triangular, with the apex bluntly 

 rounded. The inner fixed ])ranch of th(^ uropoda is as long as the ter- 

 minal segment. The outer moveable branch is about half as wide as 

 the inner branch, is very pointed at its extremity, and when folded is 

 not quite as long as the inner branch, being 1 mm. shorter. The 

 length of the inner branch is 5 mm. ; that of the outer branch is 4 mm. 



The legs are all amlndatory. 



EXOSPHiEROMA OREGONENSIS (Dana).« 



SphieroriKi oregonenxis Dana, Proc. Acad. Nat. Sci. Phila., VII, 1854-55, p. 177; 

 U. S. Hxpl. Exp. CriLst., XIV, 1853, p. 778, pi. lii, fioj. 4.— Stimpson, Boat. 

 Jour. Nat. Hist., VI, 1857, p. 509. 

 SplncrotiKi olivacea Lockington, Proc. Cal. Acad. Sci., VI I, 1877, Pt. 1, p. 45. 

 SphseroriKi oregonenMs RicHAjiDHON, Proc. U. S. Nat. Mus., XXI, 1899, p. 836; 

 Ann. Mag. Nat. Hist., (7), IV, 1899, p. 180; American Naturalist, XXXIV, 

 1900, p. 223; Harriinan Alaska Exp. Crust., X, 1904, p. 214; Proc. I^. S. Nat. 

 Mus., XXVII, 1904, p. 659. 

 Localities. — PacificGrove to Alaska; Popof Island(f rom fresh water), 

 Yakutat, and Glacier Bay, Alaska; Grenville Channel and Lowe Inlet, 

 British Columbia; Angel Island, San Francisco Bay. California 

 (Lockington Coll.); Gulf of Georgia; Alert Bay and Kadiak, Alaska; 



«The following description of Dana's, although concise, gives most of the essen- 

 tial characters of the species: Corjius hi've. Segmentum caudale breve, postice latis- 

 sime rotunatuni, supra h^eve. Styli caudales abdomen non superantes, lamelhl internii 

 multo longiore quam externa, fere obtusa, externa obtusa. Flagella antennarum 1 

 marum 2 darumque 12-14 articulata. 



Body smooth. Caudal segment short, very broadly rounded behind, smooth 

 above. Caudal stylets not reaching beyond line of extremity of abdomen; inner 

 lamella much the longer, nearly obtuse; outer ol)tuse. Flagella of antenna of both 

 pairs twelve to fourteen jointed, i.cngtli of body four and a half lines. 



