102 TERTIARY INSECTS OP NORTH AMERICA. 



Suborder CINURA Packard. 

 Family LEPISMATID^E Burmeister. 



This group has heretofore been found fossil only in amber, where 

 eighteen species of six or seven genera are known ; but a single species has 

 been found in the shales of Florissant, Colorado. 



LEPISMA Linnd 



The species provisionally placed here seems to differ decidedly from 

 known types in the structural characters of the legs, but the single speci- 

 men preserved being very imperfect, it is not at present generically distin- 

 guished. In the equality of the caudal setae it is nearest Lepisma, but the 

 legs are very different. The femora resemble closely the broad coxae of 

 some species of Lepisma, and would have been taken as coxae but for the 

 slender, elongated joint which follows ; one of the legs, too, more perfectly 

 preserved than the others, shows the short tarsus following the tibiae, and 

 leaves no room for doubt that the broadly expanded ovate disks on either 

 side of the body represent the femora, to which succeed a slender, rod-like 

 tibia of equal length and of uniform slenderness. The abdomen consists of 

 ten joints, tapering very gently, but at the extremity more rapidly. 



Two amber species were referred to this genus by Koch and Berendt, 

 one of which was thought to be almost identical with Lepisma saccharina, 

 but Menge pointed out that, notwithstanding the resemblance between the 

 two, they differ at almost every point. The group is cosmopolitan. 



LEPISMA PLATYMERA. 



PI. 12, Fig. 18. 



A single specimen in which the head, if preserved, is separated from 

 the body, and the greater part of the thorax is lost, but the whole of the 

 abdomen with the caudal setae, some of the lateral bristles, and most of the 

 legs are fairly preserved ; the latter do not appear in the figure. The 

 abdomen is slender and only slightly tapering, excepting on the last three 

 segments, which narrow more rapidly, so that the tip of the abdomen is 

 about half as broad as its base. The legs are very remarkable for the size 

 and great expansion of the femora and the contrasted linear tibiae ; the 



