428 FOSSIL PLANTS— LIAS. [dr. XXI. 



of these two divisions numerous remains of insects and plants have 

 been detected in several places, mingled with marine shells. One band, 

 rarely exceeding a foot in thickness, has been named the "insect lime- 

 stone." It passes upwards into a shale containing Cypris and Estheria 

 and is charged with the wing-cases of several genera of coleoptera, and 



with some nearly entire beetles, of 

 K& 46a which the eyes are preserved. The 



nervures of the wings of neuropterous 

 insects (fig. 460) are beautifully perfect 

 in this bed. Ferns, with cycads and 

 leaves of monocotyledonous plants, 

 and some apparently brackish and 



jb. Brodie.) in several places, while in others ma- 



rine shells predominate, the fossils 

 varying apparently as we examine the bed nearer or further from the 

 ancient land, or the source whence the freshwater was derived. There 

 are two, or even three, bands of " insect limestone " in several sections, 

 and they have been ascertained by Mr. Brodie to retain the same 

 lithological and zoological characters when traced from the centre of 

 Warwickshire to the borders of the southern part of "Wales. After 

 studying 300 specimens of these insects from the lias, Mr. Westwood 

 declares that they comprise both wood-eating and herb-devouring 

 beetles, of the Linnean genera Mater, Carabus, &c, besides grass- 

 hoppers (Gryllus), and detached wings of dragon-flies and mayflies, 

 or insects referable to the Linnean genera, Libellula, Ephemera, Hemero- 

 bius, and Panorpa, in all belonging to no less than twenty-four families. 

 The size of the species is usually small, and such as taken alone 

 would imply a temperate climate ; but many of the associated organic 

 remains of other classes must lead to a different conclusion. 



Fossil plants. — Among the vegetable -remains of the Lias, several 

 species of Zamia have been found at 

 F3 s- 4C1 - Lyme Eegis, and the remains of conifer- 



ous plants at Whitby. Fragments of 

 wood are common, and often convert- 

 ed into limestone. That some of this 

 wood, though now petrified, was soft 

 when it first lay at the bottom of the sea ? 

 is shown by a specimen now in the mu- 

 seum of the Geological Society (see fig. 461), which has the form of 

 an ammonite indented on its surface. 



M. Ad. Brongniart enumerates 47 liassic acrogens, most of them 

 ferns; and 50 gymnosperms, of which 39 are cycads and 11 coni- 

 fers. Among the cycads the predominance of Zamites, and among 

 the ferns the numerous genera with leaves having reticulated veins 

 (as in fig. 423, p. 411), are mentioned as botanical characteristics of 



