18 MIOCENE FAUNA, 



(Dineutus and Caryoborus} are now wanting in Europe, but all 

 the rest are represented both in Europe and America. As the 

 whole number of genera of beetles from (Eningen now known 

 to Prof. Heer is 156,, those common both to Europe and America 

 constitute two thirds of that number, the proportion in the pre- 

 sent beetle-fauna of Europe (according to Lacordaire) being only 

 one third. Hence the genera spread over both hemispheres were 

 more numerous in Tertiary times than at present. Of exclusively 

 European genera we find only 5 ; but there are 18 which now 

 occur in Europe and Asia or Africa, but not in America. These 

 are chiefly genera belonging to the fauna of the Mediterranean 

 region (such as Pentodon, Glaphyrus, Capnodis, Brachycerus, 

 Zonitis, Mlid], which reinforce the CEningian fauna with Medi- 

 terranean forms and the genera common to both hemispheres 

 are in part represented by species most nearly allied to those of 

 the Mediterranean region. There are two exclusively African 

 types (Lepitrix and Gymnochila) , and also two which are now 

 confined to America (Anoplites and Naupactus) . But there are 

 several genera now absent from Europe which are chiefly Ame- 

 rican, although not exclusively so (as they occur also in Asia or 

 in Africa) : such are Belostoma, Hypselonotus, Diplonychus, 

 Evagoras, Stenopoda, Plecia, Caryoborus, and Dineutus. In all, 

 (Eningen furnishes 29 species which have their nearest living 

 allies in America, and 102 which most closely approach Euro- 

 pean forms. Of the latter, the majority belong to the south of 

 Europe. 



On the whole the insect-fauna of CEningen has more of a 

 Mediterranean character, and less of a more southern and Ame- 

 rican stamp, than the flora. This applies particularly to the 

 insects with a complete metamorphosis, and less to those in 

 which the metamorphosis is incomplete, especially the Rhyn- 

 chota. By the great prominence of the Reduviidse, Scutata, and 

 Coreodea, by the large Cicadidse, the fine species of Cercopidse, 

 and the gigantic Water-bugs, the Rhynchota furnish evidence 

 of a warmer climate, and especially a milder winter, than are 

 now known in Central Europe. The cause of this may probably 

 be as follows : The insects with an incomplete metamorphosis 

 (the Rhynchota, Orthoptera, and a part of the Neuroptera) have 

 no quiescent pupa state, and the majority of them live as larvae 



