NO. 1507. FRESH-WATER AMPHIPODA—WECKEL. 29 



theiiiaffjin, and one alone near the posterior angle; the posterior edges of the lateral 

 expansions of all three of the segments furnished with a few, widely separated, jVlu- 

 mose hairs. Peduncles of the first and second pairs of caudal stylets reaching to 

 about the same point, a little beyond the extremity of the sixth segment of the 

 abdomen; the outer rami slightly longer than the inner, and those of the second pair 

 of stylets only a little shorter than those of the first. Rand of the posterior caudal 

 stylets longer than in P. affiiiis; the outer rannis rather more than twice as long as 

 the peiluncle, narrow, and tapering to an obtuse tip, both edges furnished with long 

 plumose hairs, and the outer edge with a sharp spine at tlie base of ea(;h hair. Tel- 

 son slightly longer than broad, cleft half-way to the l)ase, and each lobe tipped with 

 two short spinules and a plumose seta. There ai'e two of the peculiar papiiliform 

 appendages on the sternum of the third, fourth, and fifth segments of the thoi'ax, 

 as in P. Hoyi, but apparently none upon the second. 

 » Length from the front of the head to the tip of the telson, 6 mm. 



Of this species, I have seen l)ut a single specimen, which was dredged with the 

 last species in Lake Michigan in 40 to 60 fathoms, off Racine, l)y Pr. Stimpson, from 

 whom it was received under the manuscript name of Gaminarusjilicornis. 



This species differs remarkably from all the heretofore-known species of Pontopo- 

 re'mie, in the excessive elongation of the flagella of the antennula' and antennte, a 

 character which might be regarded by some naturalists as of generic value. The 

 very close agreement with P. affiiiis and IIoijl in all other parts of the animal, how- 

 ever, seems to indicate a very close afiinity with those species, especially the latter; 

 and as this one peculiarity is very likely only a sexual character of the old males of 

 the species, I retain the species in the genus. The mouth-appendages seem to agree 

 perfectly with those of the species just mentioned. The singular armature of the 

 lateral margins of the third segment of the abdomen is not peculiar to this species, 

 but is almost exactly repeated in P. affinis, P. Hoyi, and the marine species, already 

 mentioned, from the Gulf of St. Lawrence, and is prol)ably common to the genus, 

 although it seems to have been overlooked till now. 



Family GAAIMARID^E. 



Genus EUCRANGONYX Stebbing. 



KEY TO SPECIES. 



A. Telson about as long as peduncle of third uropods, not deejily cleft, third 

 uropods short. 

 B. Outer ramus of third uropods aliout twii-e the length of peduncle; inner 

 ramus very small, telson cleft one-third distance to base. 



C. Eyes small, elongated, with black pigment E. gracilis, p. 32 



CO. P^yes small without black pigment E. packardii, p. 35 



BB. Outer ramus of third uropods shorter than peduncle; inner ramus absent, 

 peduncle produced distally on the inner side into a short, blunt process; 



telson cleft three-fourths distance to base. _ E. bifrirms, p. 33 



AA. Telson in the male elongated, equaling from one-fourth to one-third length 

 of body, rounded distally; telson in female short, with a slight emargina- 

 tion; third uropods with short outer ramus and rudimentary inner ramus, 



E. mncronatus, p. 29 

 EUCRANGONYX MUCRONATUS (Forbes). 



Crangnmjx rnvcroiutluK Forhes, Bull. III. State Lab. Nat. Hist., No. 1, 1S7(), p. 6. — 



O. P. H.w, Am. Nat., XVI., 1882, p. 241. 

 Enrrangonyx mueronains Stebbing, Trans. Linn. Soc. London, 2nd ser., VII, 



1899, p. 423. 

 Bacirums mueronains W. P. Hay, Proc. U. S. Nat. Mus., XXV, 1902, p. 429. 



