Reviews — 8cudder^s Tertiary Insects. 281 



of Nortli America, and even now only the lower orders of Insects 

 have been fully treated ; the materials collected within the last 

 twenty years proving as abundant as all those hitherto known from 

 the entire Eiiropean area. In the Introduction the author remarks, 

 " The pages and plates of the present volume bear testimony to the 

 fact that our Tertiary strata have preserved remnants of an ancient 

 host, so varied in structure, so closely also resembling their brethren 

 of to-day, that nearly or quite every prevalent family-group in the 

 entire range of the insect world has already been demonstrated to 

 have then existed. While often fragmentary and crashed, sometimes 

 beyond recognition, a not insignificant number are sufficiently pre- 

 served for us to repopulate the past; sometimes, too, they are 

 preserved in such a wonderful manner that in tiny creatures with a 

 spread of wings scarcely more than a couple of millimetres, one ma}' 

 count under the microscope the hairs fringing the wings." 



There are several localities which have yielded the insects herein 

 described, but by far the most important is Florissant, in a narrow 

 valley high up in the mountains at the southern extremity of the 

 front Eange of Colorado. The insects are here preserved in an old 

 lake basin, probably of Oligocene age, in shaly beds, now laid bax-e 

 by erosion, which are wholly composed of volcanic sand and ash, 

 and 15 metres in thickness. These beds yielded a greater number 

 of insects in a single summer than have been obtained at the cele- 

 brated CEningen deposit in thirty years, and a very interesting 

 comparison is made of the percentage of representation of the 

 different groups at the two localities. At Florissant the most 

 nnmefously represented group is the Hyraenoptera, which forms 

 40 per cent, of the total ; followed by the Diptera with 30 per cent., 

 the Coleoptera with 13 per cent., the Hemiptera with 11 per cent., 

 and the Neuroptera with 5 per cent., whilst the Lepidoptera, 

 Orthoptera, and Arachnida together only contribute -54: per cent. 



Great numbers of plants are found associated with the insects 

 at Florissant, and both kinds of organisms indicate a climate con- 

 siderably warmer than that now prevalent in the locality. 



Of probably the same age as the Florissant deposit are the 

 insect-bearing beds of the White River in Western Coloi'ado and 

 Eastern Utah, and of two or three localities in Wyoming. From 

 fine clays of probably Miocene age, at and near Quesnel in British 

 Columbia, Dr. G. M. Dawson obtained numerous insects, mostly 

 Hymenoptera and Diptera ; which Dr. Scudder has also described. 



Of a more recent age are a considerable number of elytra and 

 other remains of beetles, obtained by Dr. G. J. Hinde in clay beds 

 near Toronto, Canada. Though only of interglacial age, the twenty- 

 nine species determined by Dr. Scudder are all extinct ; some of 

 the forms are nearly allied to insects now inhabiting the same 

 district in Canada and the northern United States, whilst the 

 relatives of others now exist in the Lake Superior and Hudson 

 Bay Region. 



The author notices some peculiar general features relating to 

 the occurrence of the fossil insects in North America ; one, that in 



