S81 



of the two discoid faces. These specimens are rare, even 

 in fragments. 



The Infusorial remains are by no means equally diffused 

 through the marl. On some occasions I have sought whole 

 days in vain for any interesting forms, but sometimes a 

 small fragment of marl has yielded me a good supply. 

 They are, however, never so plentiful as in many of the 

 localities in Italy, Germany, Hanover, Sweden, and North 

 America. The deposits of San Flora, in Tuscany, and 

 Hanover, seem to yield nearly all the species of Bridling- 

 ton ; and in CharleswortK s Magazine for 1839, and in a 

 drawing in the possession of Dr. Mantell, many of the 

 same Infusoria are noticed from Bann, in the county of 

 Down, in Ireland. 



As it thus appears from all the investigations, that there 

 are two tribes in particular which have left their minute 

 remains in such abundance, through a large series of 

 rocks, as to have been rather boldly regarded as the real 

 constituent molecules of them, I shall add a short summary 

 of their more remarkable natural characters, as determined 

 by examination of living and fossil specimens. 



1. The Foraminlfera consist of an external shell and 

 internal soft animal, which fills it. The shell is con- 

 camerated, or, to speak more correctly, is composed of 

 several cells, arranged in a series either discoid or spiral, 

 or aggregated ; the cells communicating by large openings, 

 all filled by connected tubes of the animal substance, and 

 (usually) perforated on the free surfaces by many small 

 holes, which give passage to fine cilise, or pseudopodia, like 

 the cilise of bryozoa. 



The ovary, digestive canal, &c., are known to take a 

 direction through several cells ; no nervous system has 

 yet been seen ; no vascular circulation is known ; no 

 special organs for respiration ; and in general, though the 

 shell is polythalamous, the animal is not a Cephalopod, 



X 2 



