242 TERTIARY INSECTS OP NORTH AMERICA. 



occurrence of three species of this group in Prussian amber, described by 

 Germar in Koch and Berendt's great work, and it is still more interesting 

 to find a species apparently belonging to this genus from the shales of Flor- 

 issant, Colorado. 



MONOPHLEBUS SIMPLEX. 



The single specimen referred to this genus agrees better with the fossil 

 than with recent types. It is a fairly well preserved body, with the dorsal 

 surface uppermost, but slightly turned to one side ; the wings partially 

 expanded, and all the legs of one side showing excepting the tarsi ; unfortu- 

 nately no antennae are preserved. The head is small and subcircular; the 

 thorax large, subquadrate, tapering abruptly in front to the width of the 

 head, which is hardly more than half the width of the thorax. Wings of 

 the shape of those of M. pinnatus from amber, about three times as long as 

 broad, well rounded, showing with distinctness only the subcostal vein 

 which runs from near the base toward the costa, on approaching whicli it 

 follows the thickened margin almost exactly parallel to it to the extreme 

 tip of the wing, much as is seen to be the case in M. pinnatus, though hen- 

 separated more widely from the shoulder of the wing at its base ; besides 

 these there are only visible the base of the median vein from which the sub- 

 costal takes its rise, running but an extremely short distance into the heart 

 of the wing, and a mere spur of the lower vein which arises barely before 

 the subcostal and runs into the heart of the wing a less distance than does 

 the oblique basal part of the subcostal. The legs are subequal in length : 

 the tibiae a little longer than the femora and scarcely slenderer ; all are 

 slight. The abdomen is long oval, well rounded behind, and composed 

 distinctly of nine joints, of which the penultimate is very slight but the lire- 

 ceding ones subequal, with no signs of any lateral or terminal appendages 



Length of body, 3.25 mm ; breadth of same, 1"""; length of wing, 2.5 mm ; 

 breadth, 0.8 mm ; length of hind femora, 0.7 mra ; hind tibia?, 0.75 mm . 



Florissant. One specimen, No. 7561. 



Family APHIDES Leach. 



One would hardly suppose that objects of such extreme delicacy and 

 minute size as plant lice would be found in a fossil state. Yet they are by 

 no means infrequent, and have even been found in the Secondary deposits 

 of England ; for in Brodie's work two objects which appear to be wingless 



