224 



FAMILY IV. DYTISCIDiE. 



XIV. Agabetes Crotch. 1873. (dr., " good + swimmer. " ) 



This genus contains but one short, broad, depressed species hav- 

 ing the head somewhat flattened; thorax very short, with sides 

 rounded, not margined ; prosternal spine with an acute carina. The 

 males have the anal segment deeply impressed each side, and the 

 front tarsal claws very long. 



434 (1405). Agabetes acuductus Ilarr., New Eng. Far.. 1828, 124. 



Oval, snbdepressed. Blackish or piceous, feebly shining; head, side 

 margins of thorax and humeri of elytra reddish. Disk of thorax and sur- 

 face of elytra with very numerous short scratches or impressions. Length 

 7-7.5 mm. 



Lake, Kosciusko and Knox counties; rare. April 29-Septem- 

 ber 2. 



XV. Ilybiosoma Crotch. 1873. ((jr., ' ' mud or slime + body.") 



This genus comprises two medium-sized species having the hind 

 tibia? and tarsi very short ; first tarsal joint shorter than the tibial 

 spur. The males have the front and middle tarsi compressed, nar- 

 rowly dilated; claws simple. One of the two, described from Can- 

 ada and belonging to the boreal fauna, occurs in northern Indiana. 



435 (1399). Ilybiosoma bifabia Kirby, Faun. Bor. Amer.. IV, 1837. 71. 

 Obloug-ovate, subconvex. Black, shining; head in front, antenna 1 , legs 



and side margins of thorax reddish-brown. Elytra with numerous minute 

 longitudinal impressed lines which, behind the middle, are transverse. Length 

 G-7 mm. 



Represented in the collection by a single specimen taken near 

 Pine, Lake County. May 3. 



XVI. Agabus Leach. 1817. (Or., a proper name.) 



A large number of blackish or more or less metallic, rarely varie- 

 gated beetles, ranging from 7 to 12 mm. in size and having the 

 thorax margined ; prosternum often acutely car in ate ; claws of hind 

 tarsi equal ; elytra usually very finely reticulate or alutaceous. The 

 front tarsi of the males are swollen, the joints beneath being clothed 

 with hairs which are usually tipped with minute disks. The hind 

 legs are rather feebly developed for swimming, and the beetles are 

 therefore often found under stones in wet, grassy places, or about 

 the roots of semi-aquatic plants in marshes and shallow pools. 

 More than 50- species are listed from the United States. Of these, 

 10 are known from Indiana while several others doubtless occur. 

 On account of their close similarity they are difficult to separate un- 

 less both sexes are at hand, 



