HA RD WICKE' S S CIENCE- G OS SIP. 



49 



CHAPTERS ON FOSSIL INSECTS 



By ROBERT B. COOK. 



No. II. 



N our last article 

 we very briefly 

 traced the geo- 

 logical history of 

 the orders Neu- 

 roptera, Orthop- 

 tera, Hemiptera, 

 and Coleoptera, 

 representatives of 

 all which orders 

 have been found 

 in the Palaeozoic 

 rocks ; it now 

 remains for us in 

 like manner to 

 notice those orders 

 which apparently 

 appeared later in 

 geological time. 



I. Euplexoptera. 

 — T his small 

 order, composed of the earwigs, which insects have 

 been ranked by some naturalists as Coleoptera, and 

 by others as Orthoptera, but are now generally placed 

 in a small separate order — is first represented in the 

 Lower Lias marls of Schambelen, Switzerland, by 

 one species very different from any living form, being, 

 according to Professor Ileer, more transitionary be- 

 tween Orthoptera and Coleoptera ; this insect itself 

 affording as much difficulty to correctly name, as the 

 earwigs generally have afforded in their classification. 

 Fossil earwigs have also been found in the Solenhofen 

 slate of Bavaria, the Eocene formations of Monte 

 Bolca near Verona, and of Aix in Provence, and the 

 Miocene deposits of Oeningen in Switzerland. 



2. Diptera. — Some very fragmentary specimens, 

 thought by Professor Westwood to belong to this 

 order, have been discovered in the Lower Lias for- 

 mations of the west of England ; but the oldest 

 undoubted remains come from the Purbecks of 

 England and the Solenhofen slate of Bavaria (both 

 No. 267.— M ARCH 1887. 



formations of Upper Oolitic age), and include the 

 genera Bibio, Tipula, Cecidomya, Musca, and Culex. 

 In all the Tertiary insect-bearing strata the Diptera 

 occur in great abundance, most of the existing genera 

 being represented by species more or less allied to 

 the present forms. 



3. Trichcptera. — This order, which comprises the 

 caddis flies, and which, according to Westwood, 

 "forms the connecting link between the Neuroptera 

 and Lepidoptera," appears for the first time in the 

 Purbeck beds of Dorsetshire, and occurs subsequently 

 in the Eocene beds of the Isle of Wight and of Aix 

 in Provence, while the Miocene freshwater formations 

 of Auvergne are composed in great part of what is 

 known as " Indusial limestone," so called from the 

 rock being formed entirely of the "indusise" or 

 larval cases of the caddis worms cemented together 

 by calcareous or siliceous matter ; and it is most 

 interesting to note, that the larva of the caddis fly 

 seems to have possessed the same habit then as now 

 of sticking small shells to its case, for the caddis cases 

 found in the dried-up lakes of Auvergne are very 

 often covered with the shells of a small species of 

 Paludina, thus resembling in a great measure the 

 common English species of caddis worm, which is so 

 fond of attaching to its case the small shells of 

 Planorbis nautileus, and other species. Fossil caddis 

 cases have also been found at Oeningen, Locle, and 

 elsewhere. 



4. Hymenoptera. — A small fragment of a wing 

 found in the Lower Lias marls of Schambelen, 

 Switzerland, has been assigned by Professor Heer, 

 with much hesitation and doubt, to the order Hymen- 

 optera ; but the occurrence of this solitary and 

 doubtful specimen, unconfirmed by any other Hymen- 

 opterous remains from formations of the same age, is 

 scarcely sufficient to establish so high an antiquity for 

 the order. However, in the Solenhofen slate, an 

 Upper Oolitic formation already several times re- 

 ferred to, veritable Hymenoptera occur, which have 

 been assigned to the family Apidoe. In the Tertiary 



D 



