No. 26.] ARTHROSTRACA OF CONNECTICUT. IO3 



First antennae longer than second and provided with a com- 

 paratively small accessory flagellum. 



Mouth parts normal. 



Gnathopods subchelate and unequal, the second pair being 

 the larger and being strongly developed in male. Posterior perei- 

 opods unusually robust with basal joints very large and laminar. 



Last pair of uropods not much elongated, robust, with rami 

 comparatively broad. Telson laminar and divided by a deep, 

 narrow cleft into two halves which are spinous at the tip. 



Elasmopus levis (Smith). 



1874. Mccra levis, Smith, Rep. Com. Fish., vol. i, p. 559. 



Eyes nearly round, black. 



First antennas stout, two-thirds as long as body ; first and 

 second joints of peduncle equal in length, third joint two-thirds 

 as long as second ; principal flagellum as long as peduncle and 

 made up of about 24 rather short segments ; accessory flagellum 

 less than half as long as last joint of peduncle and composed of 

 two oblong joints and a very short terminal one. 



Second antennae slender, scarcely longer than peduncle of 

 first; fourth and fifth joints of peduncle subequal, third joint 

 very short, gland cone prominent; flagellum slightly longer than 

 last joint of peduncle, made up of about eight joints. 



Mandibles with three-jointed palp of characteristic form, 

 last joint having shape of knife blade with row of setae on edge. 



First four coxal plates slightly deeper than their respective 

 segments, fourth about as broad as deep. 



First gnathopods of male, with propodus oblong and subequal 

 to carpus which is provided on posterior margin with numerous 

 setae, and with palm oblique and evenly convex ; basus stout. 

 Second gnathopods of male very large, carpus very short, with 

 narrow posterior lobe furnished with dense setae ; propodus oblong 

 and twice as long as broad, palm short, oblique, smooth, with row 

 of four or five spines near base of dactyl, which is stout and 

 closes against an excavation on inner side of propodus. 



In the female, first gnathopods much like those of male but 

 with palm transverse. Second gnathopods much smaller than in 

 male, of oblong shape resembling the first gnathopods of male ; 

 dactyl slender and closing against palm. 



