118 TERTIARY INSECTS OF NORTH AMERICA. 



width of the head. Fore tibiae slender, longer than and not half so stout 

 as the fore femora. Abdomen very short and stout, tajiering' very rapidly 

 behind. 



PerhajDS this genus is as neai'ly related to Amphientomum as to any 

 other. A single species is at hand. 



Paropsocus disjunctus. 

 PI. 5, Fig. 51. 



The single specimen unfortunately shows only an insignificant fraction 

 of neuration, and therein no distinctive parts, but only those which are 

 common to all genera of Psocidaj. So far as can be seen, the head, thorax, 

 antenna;, and legs are absolutely naked. The plate wrongly shows the left 

 antenna as the tarsus of the fore leg. The third joint of the antennae is 

 shorter than the width of the head between the eyes. 



Length of body, 1.6""; breadth of head, 0.45"""; of thorax, 0.75°"°; 

 length of third antennal joint, 0.3°"°. 



Fossil Canon, White River, Utah. One specimen, No. 33", W. Denton. 



Family EPHEMERID^E Stephens. 



Our previous knowledge of Tertiary Ephemeridse is based entirely upon 

 imagos and almost entirely confined to the statements made by Pictet and 

 Hagen nearly thirty years ago in their account of amber Neuroptera. Four 

 species of Baetis and one each of Potamanthus and Palingenia were there 

 described, and two years earlier mention is made by Hagen, by name 

 merely, of a second species of Palingenia, but in the subsequent work it is 

 refen-ed to Baetis. Here also Pictet's Palingenia is considered as more 

 closely related to Baetis anomala, for which in his monograph of the 

 Ephemeridfe Eaton establishes the genus Cronicus. Eaton also refers the 

 Potamanthus to Leptophlebia. We have therefore from the amber three 

 species of Baetis, one or probably two of Cronicus, and one of Leptophlebia. 

 Besides these, Sendel figures a species which he classes "inter ephemeras 

 minores," and Burmeister says he has seen "zwei individuen der gattung 

 Ephemera" in the Berlin Museum. 



. From the Tertiary rocks we have onlj^ a reference by Schlotheim to 

 an insect from Oeningen, which lie says may be an Ephemera or a Phry- 



