Uliler.] 108 [February 1, 



end of the abdomen in the corresponding sex. Brownish, or bronzed 

 black, the underside bluish sericeous. Head velvety black, the front 

 almost truncated, cinereous, with an impressed longitudinal line run- 

 ning almost to base, with a few long hairs about the sides and above; 

 base of cranium a little carinately elevated. Labrum and lateral 

 lobes yellowish, or rufo-piceous ; rostrum black, reaching to the tip 

 of the anterior coxae. Eyes brown. Antennas, excepting the pale 

 base of basal joint, black, basal joint stoutest, curved, about twice as 

 long as the second, the second subequal to the third, the fourth 

 decidedly shorter than the third. Thorax obese, pronotum velvety 

 black, sparingly clothed about the sides with fine golden pubescence; 

 the collum orange, interrupted in the middle by blackish, middle line, 

 faintly carinated ; tip of pronotum produced, at tip curved upwards, 

 the extreme end expanded, with a granulated process at each corner 

 ("winged) ; in the unwinged, the posterior margin forms a long tri- 

 angle with the angles bluntly rounded. Each side of prosternum 

 broadly orange. Coxae, trochanters and usually the base of femora 

 yellow ; the femora bronzed- or blue-black. Cerci of the male 

 long, slender, curved, hairy. 



Length, 31-4 millims. Greatest breadth of pronotum, 1-f 

 millims. 



No. 64. Harris Collection. " Velia collaris Say, Mss. On 

 water, September 30th." 



Occurs both with and without wings in some localities. Near 

 Baltimore and in Eastern Massachusetts I have found great numbers 

 of specimens, but always unwinged. 



Fam. HYDROMETRID^J. 

 Metrobates. Nov. Gen. 



Similar to Halobates Esch. (autor.) Robust and broad. Anten- 

 nae stout, almost as long as the entire body, the basal joint nearly as 

 long as the three others united, curved at base, narrowing in that 

 direction, much stouter in the male and expanded at the tip, the 

 underside with erect hairs; second joint about one-third the length of 

 the basal, greatly enlarged at tip, the third shortest, also enlarged at 

 tip, fourth very stout, fusiform, almost as long as the second. Prono- 

 tum ample (in the unwinged form narrow and short, the mesothorax 

 forming the stoutest and largest part of the body) , a very little 



