From the nature and proportion, therefore, of the constituent parts 

 of the coriaceous crust of the animal, and its speedy resolution, by 

 which it is prevented from passing through the several changes necessary 

 to its mineralization, we may suppose, that the rareness of its being 

 found in a petrified state chiefly proceeds. 



The remains of several species of these animals have, however, been 

 preserved, and chiefly in chalk and in lime-stone; and almost all of 

 them approximate so nearly to known recent animals, as to allow of 

 the considering them as of similar species with those which have been 

 described by Linck and other naturalists. 



The recent animals to which the fossil species appear to be referable, 

 are: 



1. Pentagonaster semilunatus ; Linck. de Stellis marinis, Tab. xxin. 

 No. 37 ; xxiv. No. 39 and 45. This fossil has been figured by Schultz, 

 Betrachtung der versteinerten, Tab. n. Fig. 6, from Pirna. A chalk 

 fossil, from the Kentish chalk-pits, in which a considerable part of this 

 lunated star is preserved, is represented Plate I. Fig. 1. M. Walch, in 

 Knorr's work, Recueil des Monumens des Catastrophes, Kc. gives the figure 

 of an impression on a flint, from New Strelitz, of a stellite of this species. 



2. Pentagonaster regularis ; Linck. Tab. xm. No. 22. A fossil asterite 

 of this species, with which I was favoured by H. H. Goodall, Esq. of 

 the East-India House, is figured Plate I. Fig. 3. This is also from the 

 Kentish chalk-pits. 



3. Pentaceros reticulatus, Linck. Tab. xxin. xxiv. No. 36, is found fos- 

 sil, in fragments, at Chassai sur Saone, according to Davila. 



4. Pentaceros lentiginosus, sen, Stella reticulata lentiginosa; Linck. Tab. XLI. 

 and XLII. I lately obtained a stellite of this species, or very nearly 

 approaching to it, from one of the Essex chalk-pits. The specimen, 

 though large and handsome, and possessing the general form of this 

 animal, would not have given the idea of this particular species, per- 

 haps, if the two rows of mamillae, or rather bones, had not still existed 



