THE CANADIAN ENTOMOLOGIST. 119 



general, are longitudinal in direction, but behind the middle slope some- 

 what towards the suture. The front of the head and the legs are red. 



' COPELATUS, Er. 



Here belongs C. glyphicm, Say, which is peculiar on account of the 

 distinct elytral strife. Colour rufo-piceous, legs paler. Length, , 19 to .24 in. 



Matus, Aube'. 



Elongate, brownish-red, thorax rounded at the sides, anterior angles 

 acute. Length, .32 in. Easily recognized by the elongate form and 

 peculiar colour. Our species is M. bicarinatus, Say. 



Agabetes, Crotch. 



Oblong-ovdl, black, beneath reddish. Thorax very short, sides 



rounded, lateral margin reddish ; elytra with reddish humeri, the 



surface covered with minute short scratches. Length, .27 in. A. 



acuductus, Harr. 



Agabus, Leach. 



The species of Agabus are very numerous, and, from their extreme 

 similarity in some parts of the series, difficult to separate. While none of 

 them are very large, most of them are. above a quarter of an inch in 

 length ; the colour is usually blackish, often more or less metallic, rarely 

 variegate. They may often be found under stones in wet grassy places, 

 or around the roots of plants in marshes and shallow pools ; the swimming 

 legs are usually rather feebly developed. 



It has been deemed unwise to attempt a synoptic table, several of 

 the Canadian species not being at hand for study. We have, therefore, 

 been content to follow in the main the arrangement of Mr. Crotch, with 

 the addition of such species as have been described since the publication 

 of his paper, and such changes of nomenclature as seem necessary to 

 bring it into correspondence with recent researches. The groups are 

 based on the form of the male claws, the females offering too few char- 

 acters of value to enable them to be identified in many cases without the 

 corresponding males. This latter sex has the anterior tarsi more or less 

 swollen, the joints beneath being clothed with hairs usually tipped with 

 minute disks. 



Group I. Anterior external claw in the $ very elongate, broadly 

 dilated, internal one elongate and sinuate. 



A. erythropterus, Say. Oval, convex, black, opaque ; legs, margins 

 of ventral segments and elytra yellowish brown, the sides and humeral 

 angles paler. Surface of elytra closely reticulate, dorsal punctures 

 obsolete. .37 in. 



