346 TEETIAEY INSECTS OF NORTH AMERICA. 



Length of body, 6 min ; of tegmina, 5 mm ; breadth of closed tegmina, 

 2.85 mm . 



Florissant. Three specimens, Nos. 1456, 2238, G978. 



Family NOTONECTID^E Stephens. 



This family of water-bugs makes its first appearance in the Tertiaries, 

 and then in very scanty numbers. But four species are known, all of them 

 referred to the existing genus Notonecta, which has now a wide distribu- 

 tion. The three known European fossil species have been reported respect- 

 ively from Kutschlin, Rott, and Aix. The fourth is the species from Flor- 

 issant, described below. 



NOTONECTA Linne*. 



A single small species of this genus has occurred at Florissant of a sim- 

 ilar size as, but of a more robust form than, the species described by Deich- 

 miiller from Kutschlin ; a second larger species has also been described by 

 Heyden from Rott, and a third has been indicated by Hope from Aix. 

 Existing species of the genus most abundant in temperate regions are found 

 nearly all over the world. 



NOTONECTA EMEESONI. 

 PI. 22, Fig. 11. 



A small species, of which possibly only immature individuals are at 

 hand. The smaller showing the dorsal surface is certainly so, and the other 

 showing the ventral surface is not clearly determinable in this respect. The 

 description is taken mainly from the larger. It is of a very regular oval 

 form and is apparently mature, since on one side is seen the edge of the 

 hemelytra, or what can hardly be regarded otherwise. Fringes of combed 

 hairs are directed obliquely backward on the sides of the abdomen, and the 

 median forked line on its posterior portion seems to indicate the hemelytral 

 suture of the upper surface seen through the body. The hind legs are of 

 the usual type, terminating in a blunt point blunter than appears in the 

 figure, and are minutely fringed with delicate short spines. The femur, 

 tibia, and first tarsal joint are subequal. 



