IN THE MUD OF THE LEVANT. 53 



tion of their organic origin, a matter of some 

 difficulty. They would have much of the aspect 

 of the crystalline atoms, found in many strata, 

 which have been supposed to result from chemical 

 precipitation. This tendency to separation, exist- 

 ing amongst shells, is important in its bearing 

 upon the origin of calcareous rocks, and one to 

 which I shall have to recur. 



Numerous fragments of Echinodermata may 

 also be observed. Some of these are the partially 

 developed rudimentary plates, as in Figs. 50, 51, 

 52.* Others consist of the cribriform fragments 

 of matured animals. Fig. 53 — easily identified by 

 those who are familiar with these interesting 

 organizations. There are also some Cytherae — 

 minute marine Entomostracous Crustaceans — 

 allied to the genus Cypris, so common in our 

 fresh-water pools. 



Before comparing the result of a microscopic 

 examination of the Levant mud, with what is 

 observed on an examination of the older strata 



* See Agassiz' Mouographies d'Echinodermes vivantcs et 

 fossiles — quatrieme livraison. Aaatotnie du genre Echinus par 

 (J. Valentin. Table o., figs. 65, GG, G7. 



