65 
existence at the Cretaceous epoch, some few may have escaped general 
destruction. A continuance of species is more possible and probable 
in these minute and low organized creatures than in the higher orders 
of animals. 
No part of the Chalk formation has been the subject of so much 
diversity of opinion as the origin of Flint*. With respect to one 
species of remarkable products of the chalk, called paramoudras, Dr. 
Buckland has recorded some valuable observations which bear upon 
the theory of the origin of siliceous bodies in general. He says (‘ Geo- 
logical Transactions,’ vol. iv. 1817, pp. 416, 417, 418), ‘In all these 
cases the organic bodies thus preserved appear to have been lodged in 
the matter of the rock while it was in the state of a compound, uncon- 
solidated, pulpy fluid; and before that separation of its siliceous from 
its calcareous ingredients, which has given origin to the flinty nodules 
in chalk, and to beds and nodules of chert in other limestone rocks. 
The present shape of many chalk flints being that of organic bodies, 
demonstrates the latter to have existed before the consolidation of the 
former; for the fidelity with which the silex has often copied the 
organization, and even the accidents and irregularities of the bodies 
enveloped, is so accurate, that it is impossible to attribute the form of 
the flint to any other cause than that of the body on which it was de- 
posited. Sometimes the organization is so delicately retained, that it 
seems not to have undergone the smallest derangement before the 
siliceous cast was taken; and the model is thus permanently pre- 
* When first extracted from the quarry, flint is brittle, has a conchoidal fracture and feeble 
lustre ; thin fragments are transparent ; its specific gravity is 2°594. According to the analysis 
of Klaproth, it consists of— 
Silex] jeter etes leds cbc meotice 198 
1 ros by ca, og. ey SL ERS che Ce ‘O05 
Alumine Wagener, eee: “025 
Oxidetofelronpeaer ses PS 025 
Water Jit GYM ayery Guzentaears «s ili 
