VI. — Coleopierological Notices. 

 VII. 



BY THOS. L. CASEY. 



Read Nov. 16, 1896. 



All taxonomic investigation, in fields touched upon in the fol- 

 lowing studies, must be more or less imperfect at the present stage 

 of knowledge of the arthropod fauna of the world. This can be 

 brought prominently into evidence, if we consider the usual pro- 

 portion of previously described species contained in any inde- 

 pendent collection subsequently made, in any particular group 

 and over the same geographic area. Although this new collec- 

 tion may comprise several times the number of species previously 

 known, it is virtually safe to say that there will be a considerable 

 proportion of the latter unrepresented. In this way we may be 

 enabled to foretell in a measure the real extent of the particular 

 group in any given region. 



For example, the revision of the Scydmsenidae, which is includ- 

 ed below, makes known some 175 species as inhabiting the United 

 States. If an independent collection were now formed, contain- 

 ing 115 species, it would probably include at least 75 not men- 

 tioned in this revision. The next independent set of 175 would 

 include perhaps 10 per cent, less of unknown forms, or say 68, 

 the next 61 ; then in succession 55, 50, 45,41, 37, 33, 30, 27, 24, 

 22, 20, 18, 16, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5 and 4, making a total 

 of 721, which, added to the original 175, would indicate about 

 896 species. This, of course, is an almost purely fanciful suppo- 

 sition, and yet it is possibly not so very far wide of the truth, 

 judging from isolated sets of species received from time to time. 

 There should be but little hesitation in stating that there are 

 within the American continent, north of Mexico, about 1,000 

 species of Scydmsenidse, 2,000 of Pselaphidse, 10,000 of Staphyl- 

 inidse and 80,000 of the order Coleoptera. As a corollary to this 



Annals N. Y. Acad. Sci., IX, February, 1897.— 20. 



