234 Prof. BucKLAND on CoproUtes. 



occur as loose pebbles upon the shore, having- been washed out of the lias ; 

 but many are also found dispersed, like Septaria, in the lias shale, and some- 

 times in the stone lias. Occasionally they form the nuclei of small Septaria, 

 or have selenites or crystals of sulphate of barytes adhering to, and radiating 

 from, their surface. These imbedded specimens have undergone no process 

 of rolling, but retain their natural form, as if they had fallen from the animal 

 into soft mud, and there been preserved undisturbed until it was consolidated 

 to the state of lias and lias shale. 



The certainty of the origin I am now assigning to these Coprohtes, is esta- 

 blished by their frequent presence in the abdominal region of the numerous 

 small skeletons of Ichthyosauri, which, together with many large skeletons of 

 Ichthyosauri and Plesiosauri, have been found in the cliffs at Lyme, and sup- 

 plied to various collectors by the skill and industry of Miss Mary Anning. I 

 have two of these skeletons, in each of which the Coprolites are very apparent, 

 but flattened ; and Miss Anning informs me that since her attention has been 

 directed to these bodies, she has found them within the ribs or near the pelvis 

 of almost every perfect skeleton of Ichthyosaurus which she has discovered. 

 She further informs me, that whereas in the entire thickness of the lias for- 

 mation there are certain strata that abound in bones, whilst in others they are 

 comparatively rare ; so also the so-called Bezoars are most abundant in those 

 parts of the formation in which the bones of Ichthyosauri and Plesiosauri are 

 most numerous. \ 



I propose to assign the name of Ichthyosauro-coprus to the fossil fseces which 

 are thus evidently derived from Ichthyosauri*. 



In variety of size and external form the Coprolites at Lyme Regis resemble ! 



oblong pebbles or kidney-potatoes. They, for the most part, vary from two 

 to four inches in length, and from one to two inches in diameter. Some few 

 are much larger, and bear a due proportion to the gigantic calibre of the ! 



I 



* We are as yet without direct evidence to show which of the Coprolites are derived from I 



Plesiosauri ; the discovery of a skeleton containing them within it, will probably ere long decide 1 



the question : from the smaller size of their jaws, it should seem the Plesiosauri were less i 



voracious, or at least less qualified to swallow large animals, than their neighbours the Ichthyo- 

 sauri ; — still they were carnivorous and swallowed their prey entire, and must have contributed 

 their due proportion to the stores of Coprolites that lie buried with them in the lias. There is j 



sufficient variety in these Coprolites to allow them to be referred to more than one genus, and { 



to many species of Saurians. At present we can with safety apply the term Ichthyosauro-coprus to j 



those only which are found within the skeletons of Ichthyosauri, and to specimens like those en- j 



graved at Plate XXIX. figs. 2. & 5. which contain bones of animals too large to have been 

 swallowed entire by a creature having so small a mouth as the Plesiosaurus dolichodeirus. There 

 is no third genus of animals in the lias to which we can refer these largest Coprolites. 



