LIAS FORMATION. 165 



REMAINS OF VERTEBRAL ANIMALS. 



A large thick fish is rarely found in the lias shale, with solid bony scales. Heads, 

 vertebras, paddles, and scattered bones of saurian animals have been frequently ex- 

 tracted from the upper shale, and several tolerably complete skeletons have been pre- 

 served. There appear to be several species, but farther inquiries must be instituted on 

 this subject. The Museum of the Whitby Philosophical Society contains some of 

 the most valuable of these remains, particularly a small but perfect ichthyosaurus, 

 containing one hundred and thirty-six vertebrae, and a superb crocodile fifteen feet long. 

 PL XII. fig. 1, represents the basal surface of a small cranium of a crocodile, to shew 

 the arrangement of the posterior bones, and fig. 2 is a copy of a singular head which 

 seems to differ from any hitherto described fossil animal. Both specimens are in the 

 Museum of the Yorkshire Philosophical Society, 



THE three divisions of the lias formation which have been described 

 on the coast of Yorkshire, may be traced southward through Lincoln- 

 shire, Rutland, Northamptonshire, Oxfordshire, Gloucestershire, and 

 Somersetshire. Sections obtained in any part of this long range, agree 

 in representing the lias clay, as divided into two portions by an inter- 

 mediate series of sandy and irony layers of stone, full of many organic 

 remains. The upper division varies in thickness, and changes much in 

 aspect and composition. Its thickness in Yorkshire sometimes equals 

 two hundred feet, and in Rutland exceeds one hundred feet ; but in the 

 neighbourhood of Bath may be stated at twenty feet. The marlstone 

 series maintains a general conformity of character, and, though nowhere 

 so thick or so much developed as in Yorkshire, constitutes an important 

 feature in the range of the formation, especially in Rutland. The solid 

 beds of gryphitic limestone which lie toward the base of the lias clay, 

 from Somersetshire to Lincolnshire, may, with attention, be traced in the 

 southern part of Yorkshire, but they nowhere appear on the coast. Mr. 

 Murchison's observations in the district of Brora and at various points 

 on the western coasts of Scotland, are decisive as to the occurrence of 

 the lias there ; but I am unable to determine what particular divisions 

 of the formation are exposed in the several localities. With great dif- 



