EARLY SUMMER INSECTS. 131 



fruit at that time, just in the same way as the Canarian vinhatico 

 (Persea indica, Linn., sp.). On another slab there is a similar 

 fruit side by side with leaves and bud-scales of the camphor- 

 tree ; and such bud-scales are thrown off in the spring. Even 

 if the Swiss cinnamon (Cinnamomum Scheuchzeri) had borne 

 fruit during the winter, the climate in that season must have 

 been very mild. 



In the preceding description Prof. Heer has had under con- 

 sideration plants which are very nearly allied to or homologous 

 with living species, so that he could compare the phases of their 

 development with those which are directly accessible to observa- 

 tion at the present time. But even with regard to the extinct 

 types of plants some information may be obtained, as the insects 

 here assist in the research. On a slab from (Eningen side by 

 side with the ripe delicately formed fruits of the Podogonia, 

 winged ants are seen. The species (Formica lignitum and pin- 

 guis) are most nearly allied to the large wood- ant (F. herculeana] . 

 The winged individuals of the latter swarm between the begin- 

 ning and the middle of the summer, when they quit their nests 

 in immense bands and pair in the air. Hence, like all the 

 winged ants, which often appear in incalculable numbers and 

 not unfrequently perish by millions in Swiss lakes, this insect 

 announces summer. The winged ants lying beside the fruits of 

 the Podogonia therefore supply evidence that those trees ripened 

 their fruit in the summer. If this be the case, the season of 

 flowering must have occurred very early in the spring ; and in 

 favour of this view we have a leafless poplar-twig which lies 

 beside an equally bare flowering twig of Podogonium. From this 

 we learn further that in the Podogonia the flowers appeared be- 

 fore the leaves, in accordance with the well-known rule in very 

 early-flowering trees and shrubs. At the end of March, however, 

 they were in leaf; for we find a leaf with some willow-flowers on 

 the same slab. 



These are all inferences founded upon ascertained facts ; and 

 they form the starting-point from which we may endeavour to 

 form the following general view of the course of the seasons in 

 the (Eningian period of the Miocene formation. 



The ^Podogonia (fig. 196, vol. i. p. 367) were probably the first 



K2 



