TERTIARY INSECTS OF NORTH AMERICA. 



first subcostal and second median cells, although the vein above the third 

 median cell is bent where it should join it, as in the preceding species ; the 

 snine vein is partially obliterated in the middle of the portion below the first 

 subcostal cell; the vein separating the third and fourth median cells is 

 strongly curved, siibsinuate and distinct throughout. 



Length of wing, 8.4""": breadth bevond the stigma, 2.4' 1 "" ; greatest 

 width of the third costal cell, 0.4""". Formica arcana lies on the same stone. 



< ( )iiesnel, British < 'olumbia. One specimen, Nos. Id 1 ' and 12 ( I >r. G. 

 M. Dawson, Geological Survey of Canada). 



PlMPLA DECESSA. 

 PI. 3, Fig. 27. 



rii}/la dcueKsa Scuilil., Rep. Progr. (Jeol. Surv. C'au., 1675-1876, 269 (1877). 



The remains of this insect consist of crushed thorax and abdomen, and 

 the two wings of one side of the bod}', superimposed; upon the same stone, 

 at a slightly higher level, is the specimen of Holetina sepulta. The thorax 

 and abdomen are entirely crushed and black, but the last segment of the 

 latter bears the closest possible resemblance to the abdomen of the male of 

 Pimpla instigator Fabr. The wing is uniformly infumated, and the margins 

 of the anal excision infuscated ; it is covered very profusely with short 

 microscopic tapering hairs, more irregularly distributed than in the other 

 two species described, averaging in the third median cell 0.03""" in length, 

 and seated on chitinous annul! varying in size, some being but half as large 

 as others, the larger ones measuring about 0.007""" in diameter; the veins 

 are black and the large triangular stigma almost as dark, a little paler 

 toward either extremitv ; the stigma is about twice as long as broad, and 

 extends more than half-way down the upper border of the first subcostal 

 cell, the vein being partially obliterated beyond it ; the third costal cell is 

 rather narrow apically, although the tip of the wing is pretty well rounded. 

 The species may readily be distinguished from those described above by the 

 shape of the areola, which is pretty regularly quadrate, twice as long as 

 broad, and has the vein next the third costal cell obliterated only at the 

 ends; there is no trace of the vein separating the united first subcostal and 

 second median cells, and the vein separating these cells from the third 

 median cell is bent in the middle, and nearly obliterated in the middle halt; 



