326 Coleopterological Notices. 



phus, are peculiar to Europe and without any immediate allies in 

 North America, while the interesting- genera Arthrodeis, Erodius 

 and Adesmia are represented by a few species of Edrotes, of very 

 much smaller size and much less conspicuous variety. 



The European Asida and Blaps are almost exactly equaled in 

 extent and variety by the American Asida and Eleodes, but while 

 there are very few other palaearctic genera exhibiting much persist- 

 ence of type, a considerable part of the remainder of the nearctic 

 fauna is made up of large genera, composed of small, less striking 

 and more monotonous forms, such as Eurymetopon, Emmenastus, 

 Coniontis, and Blapstinus. Even Opatrum, which appears to 

 replace our Blapstinus to a great extent, is composed of very much 

 larger and more varied species. On the other hand, however, such 

 peculiar forms as Sepidium, Elenophorus and Cephalostenus may 

 fairly said to be offset by our much more numerous Zopherini and 

 Embaphion. 



A greater diversity of climatic and other physical conditions 

 prevailing in Europe is, in all probability, the direct cause of the 

 condition referred to, and the Tenebrionidas are not the only family 

 which exhibits this superior elaboration, if such an expression be 

 allowable, for the same is observable to some extent in the Carab- 

 idae ; but, as a partial compensation, the American Staphylinidae 

 exceed the European in abundance and in diversity of type, to a 

 corresponding degree. 



This may possibly be a collateral proof that the Staphylinidae are 

 older geologically than the Tenebrionidae (see Ann. N. Y. Acad. V, 

 p. 195), especially if we assume that early and comprehensive types 

 are more readily modified by environment than the later and more 

 specialized, for during the epochs immediately succeeding the Carbo- 

 niferous, North America probably possessed conditions far more 

 varied than those which then prevailed in Europe; consequently 

 the primitive and synthetic types of any family which may happen 

 to have existed at that time, would be more diversified, and would 

 transmit to the present a still more numerous and varied set of 

 typical forms. As the conditions which now make Europe superior 

 to America in evolutionizing power, were not brought about until 

 the Tertiary, it follows that any family which had its origin near 

 this epoch would be at present the more differentiated in Europe. 



