152 EVOLUTION IN THE PAST 



been brought to light ; and insect-eating birds, and other 

 animals with like tastes, certainly had a variety of victims 

 at their mercy. Many of the insects have been found en- 

 tombed in amber cast ashore by the Baltic waves. As amber 

 is the fossiUsed gum of certain pine trees, the httle animals 

 evidently got caught in the liquid resin, and were unable to 

 extricate themselves. Much additional evidence of an 

 abundant and varied insect-life has been found in other parts 

 of Europe, and in the State of Colorado, U.S.A. 



At the close of the Cretaceous Period aU the Orders into 

 which insects are now divided were to a certain extent 

 represented ; unless indeed thrips — first known in the Oligo- 

 cene — are regarded as a separate Order. The Oligocene 

 record brings out the fact that in some of these Orders there 

 had been a great branching out into famihes. Among the 

 " straight-winged " insects (Orthoptera) forms had appeared 

 of " praying " insects — so called from the devotional attitude 

 they occasionally assume (Mantidce). Saw-flies (Tenthredi- 

 nidcB), gaU-flies {Cynipidcs), wasps (Vespd), hornets (V. 

 crabroniformis), and new forms of bees — apparently honey- 

 bees {Apis proava) and bumble-bees (Bombus) — diversified 

 the ranks of 'the " membrane- winged " Order (Hymenoptera). 

 The " sheath- winged " Order (Coleoptera) was reinforced 

 by tiger-beetles (CicindelidcB), stag-beetles {Lucanidce), pill- 

 beetles (Byrrhidce), and blister-beetles (CantharidcB). In the 

 " double-winged " Order (Diptera) gad-flies and bot-flies had 

 now arisen, much to the annoyance, no doubt, of the mammals 

 (TabanidcB, (Estridce) ; but they were doubtless held in check 

 by spiders, which at this time were exceedingly numerous. 

 In the scale-winged Order (Lepidoptera) new forms of moths 

 were on the wing, including hawk-moths (SphingidcB) and 

 violet-moths (Noctuidce). Butterflies also were here and 

 there fluttering about. These greeted guests of the flowers 

 seem to have been allied to the " blues," " meadow 

 browns," and " tortoise-sheUs " of our own day {Lyccenidce, 

 Satyrites, Nimphalides). 

 VEGETATION The vegetation in Europe was of much the same character 

 as in the Eocene, indicating a continuance of high tempera- 

 ture. Palm trees were flourishing on the northlands of 



