NO. 1507. FRESH-WATER AMPHIPODA—WECKEL. 51 



Eyes not observable in alcoholic specimens. Secondary flagelluni of the anten- 

 nulae very small, composed of two segments, of which the terminal is very short. 



First and second pairs of legs diffei'ing but httle in the two sexes. First pair 

 stouter than the second, and with the palmary margin of the propodus much more 

 oblique; the palmary margin of the propodus of both pairs, and in both sexes, armed 

 on each side with a series of stout, obtuse si:)ines, with a notch and a cilium near the 

 tip. 



First three segments of the abdomen longer than the last three of the thorax; 

 fourth, fifth, and sixth together scarcely longer than the third. Caudal stylets all 

 extending to about the same point. First pair with the rami subequal, scarcely half 

 as long as the peduncle. Peduncle in the second pair reai'hing a little beyond the 

 peduncle of the first pair; the rami very unequal, the outer only half as long as the 

 inner. Posterior pair scarcely as long as the telson; the single terminal segment 

 very small, and tipped with four or five setiform spinules. Telson two-thirds as 

 broad as long, tapering very slightly toward the entire and slightly arcuate posterior 

 margin, which is armed with about ten slender spinules. 



In the largest male seen, 13.5 mm. in length (excluding the antennae), the anten- 

 nulge are about 5 mm. long, the flagellum being twice as long as the peduncle and 

 composed of about twenty-two segments, wliile the antenn;e are stout, fully 6 mm. 

 long, and the flagellum as long as the peduncle, and composed of fifteen segments. 

 All the females and most of the males which I have seen are much smaller, being 

 6 mm. to 8 mm. in length, and in these the antennula? are longer than the antennae; 

 and the flagellum of the antennulie is composed of sixteen to nineteen segments, 

 while that of the antennae has only eight to ten. 



The only specimens which I have seen were found in wells at Middletown, Conn., 

 and were sent to me by Mr. G. Brown Goode. 



Genus STYGONECTES M/ . P. Hay. 

 STYGONECTES FLAGELLATUS (Benedict). 



Crangonyx JiageUatus Benedict, Proc. U. S. Nat. Mus., XVIII, 1896, p. 616. 

 Crangonyx boiversll Ulrich, Trans. Amer. Microscopical Soc, XXIII, 1902, p. 85, 



pi. XIV. 



Slygonectesflagellatiig W. P. Hay, Proc. IT. S. Nat. Mus., XXV, 1902, p. 429. 



This blind species is closely related to Eucrangonyx macronatus 

 (Forbes). It is, however, larger and much stouter. The head, which 

 is slightly longer than the tirst thoracic segment, is proportionally 

 narrower and more concave at the insertion of the upper antennte than 

 in Eucrcmgonyx inucro7iatu)<. 



First antenna? as long as the body; first two segments of the peduncle 

 about equal and three times as long as the third; flageHum composed 

 of forty to sixty segments; secondary flageHum extending slighth' 

 bej'ond the basal segment of the primary one, composed of two seg- 

 ments, the first about four times the length of the second. Second 

 antenna slightly less than half as long as the first pair; peduncle 

 exceeding that of the first pair in length; two distal segments much 

 elongated and nearly equal; flagellum not quite so long as the peduncle, 

 composed of twelve to eighteen segments. 



Propodus of the first gnathopods in the male about two-thirds as 

 broad as long; lateral margins only slightly convex, the posterior 



