APPENDIX. 



AN ABSTRACT FROM THE LATE WORK OF DR. EHRENBERG 

 ON THE INFUSORIA BELONGING TO THE CHALK 

 FORMATIONS. 



THE author states in 1837 he communicated to the 

 Berlin Academy the discovery of Synedra ulna, &c. in 

 the polishing slate (Poler Schiefer) of Oran ; and in 

 December, 1838, that five or six species of Infusoria 

 existed in some of the chalk formations, which were so 

 similar to existing species that they afforded no tangible 

 marks of difference, and, therefore, did not authorize the 

 adoption of new names. Since then he has prosecuted 

 the investigation, the result of which is given hereinafter. 



In the introduction Dr. E. states that one of the most 

 remarkable facts elicited in the course of his examination 

 of the sea water, whilst in a state of phosphorescence, was, 

 the presence of several species of two genera, the members 

 of which have siliceous loricae, which are abundant, not 

 only in the chalk marls of Caltanisetta, Sicily, Oran, Zante, 

 and Greece, but are those forms which, from the incalcu- 

 lable number of their very minute loricae, compose the 

 chief portion of the marls which depend for their origin 

 on the remains of species of Infusoria ; and further, that 

 they belong to genera, species of which had not then been 

 seen in the living state. Subsequently the greater number 

 were taken in a live condition to Berlin, by Dr. Ehrenberg, 

 who has come to the conclusion that, from amongst these, 

 Actinocyclus senarius, Coscinodiscus patina, and Gallic- 



