Glacial Period on the present fauna of N. America. 183 



It should be noted that this series, in contradistinction from 

 the European, does not include any forms from the peat, 

 regarding which nothing has jet been published. I may 

 however add that I have studied a very large collection of peat 

 insects from Massachusetts and have so far separated over 60 

 species of Coleoptera, of which 27 are identified with existing 

 forms, 10 are probably the same as species now living, and 

 only one, a Hydrocanthus, is certainly different from anything 

 yet known. The study of the remainder has not been con- 

 cluded. 



In our own country, then, the coleopterous fauna of the 

 peat is practically identical with that now living ; while that 

 of deposits further removed from the present, out laid down 

 since the beginning of the Glacial Period, is practically entirely 

 extinct. When the early Quaternary Coleoptera of Europe 

 have been attentively studied, I believe that the same conclu- 

 sion is likely to be drawn from them. It thus appears that in 

 this country the Coleoptera are at least as sensitive standards 

 of climatic or faunal changes as are the Mammalia, which have 

 hitherto been regarded as the only group of animals any con- 

 siderable portion of which have become extinct in quaternary 

 times; and that they are more sensitive tests than other groups 

 of animals or than plants. 



Having for these reasons selected iasects as the best subjects 

 for investigation, I have further restricted myself to Coleop- 

 tera, as the order which has been longest studied, is best known, 

 and is most numerous in described species, the greater part of 

 which have had the benefit of monographic revision. The 

 main difficulty, that the catalogues give no indication of the 

 geographical distribution of the different species, has been com- 

 pletely removed by the signal kindness of my friend Mr. 

 Samuel Henshaw, who has liberally allowed me the freedom of 

 his manuscript catalogue, in which he has placed against each 

 species every published indication of special locality or general 

 range, besides those furnished by his own knowledge. 



The following table gives in detail for each family of Cole- 

 optera the result of my examination of Mr. Henshaw's cata- 

 logue, and includes over 7500 species. For brevity, I have 

 designated the drift-covered area of the east as D ; the drift- 

 less area of the same as E ; tlie northern portion of the Pacific 

 region as !N" ; and the southern as S. The first figure in each 

 column indicates the number of genera, the second of species. 

 The sign >, as in S>N, indicates that the numbers in that 

 column are the number of genera found in S and not occur- 

 ring in N, and the number of species in those same genera 

 occurring in S. The sign +, as in S + IST, means the number 

 of genera common to both S and 1ST and the number of species 



