240 



FAMILY Y— GYBIKIM. 



men darker. Elytra broad, tapering but little behind, tips subtruneate. 

 outer angle rounded; covering the entire abdomen (male) or leaving only 

 the tips exposed (female). Length 3.S-4.2 mm. 



Taken only along the borders of Wawasee and Hudson lakes, 

 where it was found in very large colonies. July 15-July 18. 



469 (1519). Gyrinus affinis Aube, Spec. Gen.. VI, 1838, 669. 

 Elongate-oval. Black, moderately shining; upper surface minutely alu- 



taceous, margins bronzed ; beneath dusky bronzed, the last ventral seg- 

 ment reddish-brown. Elytra with tips more concave than usual, their' 

 punctures fine, close-set. Length 6.5-7.5 mm. 



Putnam County; scarce. July 4. 



470 ( ). Gyrinus piceolvs sp. nov. 



Oval, moderately convex. Black, polished, the suture and side mar- 

 gins of elytra bronzed; under surface black, the last ventral paler; epi- 

 pleura and legs reddish-brown. Elytra 1 punctures well marked, the outer 

 two rows coarser. Length 5.5 mm. 



Lake County; rare. May 5. 



471 (1521). Gyrinus analis Say. Trans. Amer. Phil. Soc, II, 1823. 108; 



ibid. II, 520. 



Elongate-oval. Black, bronzed both above and beneath ; upper surface 

 not highly polished; beneath black, legs and last ventral segment reddish- 

 brown. Elytra with tips broadly but obtusely rounded. Length 5-6 mm. 



Throughout the State ; common. April 11-October 23. 



472 (1527). Gyeinus borealis Aube, Spec. Gen.. VI. 1838, 692. 



Broadly oval. Above black, highly polished, margins and sides of ely- 

 tra bronzed; beneath black, the last ventral segment dark brown. Punc- 

 tures of elytra 1 stria? fine, rather close. Length 7 mm. 



Throughout the State; frequent, April 2 3- August 15. Re- 

 sembles ventralis hut broader and with under surface black. 



473 (1528). Gyrinus lugens Lee, Proc. Phil. Acad. Xat. Sci.. 1S68, 369. 

 Broadly oval. Resembles borealis, but above black, slightly polished. 



not at all bronzed; beneath black, the last ventral segment dark brown. 

 Elytra with tips more rounded and with outer angles less distinct; punc- 

 tures finer, more distant one from another. Length 6 mm. 



Lake and Laporte counties : scarce. May 20-July 15. 



G. pectoralis Lee. is a boreal species which may occur in north- 

 ern Indiana. 



II. Dineutes McL. 1819. (Gr.. ' k to whirl or swim in an eddy.") 



The species of this genus are all of fair size, more or less oval 

 and subdepressed. They have the upper surface usually shining, 



