DISTRIBUTION 



319 



FIG. 298. Palcroblat- 

 tina doHi'illci, natural size. 

 -After BROXGXIART. 



Many fine fossils of the Jurassic period have been found in the litho- 

 graphic limestones of Bavaria; 143 species from the Lias four fifths of 

 them beetles were studied by Heer. 



The Tertiary period has furnished the majority of fossil specimens. 

 To the Oligocene belong the amber insects, of which 900 species are known 

 from Baltic amber alone, and to the same epoch are ascribed the deposits 

 of Florissant and White River in Colorado and of Green River, Wyoming. 

 These localities the richest in the world have 

 been made famous by the monumental works 

 of Scudder. At Florissant there is an extinct 

 lake, in the bed of which, entombed in shales 

 derived from volcanic sand and ash, the re- 

 mains of insects are found in astonishing pro- 

 fusion. For Miocene forms, of which 1,550 

 European species are known, the (Eningen beds of Bavaria are celebrated 

 as having furnished 844 species, described by the illustrious Heer. 



Pleistocene species are supplied by the peats of France and Europe, 

 the lignites of Bavaria, and the interglacial clays of Switzerland and 

 Ontario, Canada. 



Silurian and Devonian. The oldest fossil insect known consists 

 of a single hemipterous wing, Protocimex, from the Lower Silurian of 



Sweden. Next in age comes 

 a wing, Palceoblattina (Fig. 

 298), of doubtful position, 1 

 from the Middle Silurian of 

 France. Following these are 

 six specimens of as many re- 

 markable species from the 

 Devonian shales of New 

 Brunswick. The specimens, 

 to be sure, are nothing but 



broken wings, yet these few fragments, interpreted by Dr. Scudder, are rich 

 in meaning. All are neuropteroid, but they cannot be classified satisfac- 

 torily with recent forms on account of being highly synthetic in structure. 

 Thus Platephemera antiqua (Fig. 299), though essentially a May fly of 

 gigantic proportions (spreading probably 135 mm.), has an odonate type 

 of reticulation; while Xenoneura (Fig. 300) combines characters which 

 are now distributed among Ephemeridae, Sialidae, Rhaphidiidae, Con- 

 iopterygidae, and other families, besides being in many respects unique. 



FIG. 299.- 



-Platephemera anliqua, natural size. After 

 SCUDDER. 



1 There is some evidence, it should be said, that this species is not an insert. Tlundlirsch 

 denies also that Prolccimcx is an insect. 



