LIFE ON THE EARTH. 85 



to the extent of 736 species have been recorded in 

 the British strata, Marine Reptiles, which are less 

 numerous, and Cetacea, which are rare. 



Amorphozoa offer in this respect little for remark. 

 Belonging to the lowest grade of animal organiza- 

 tion by some naturalists of eminence counted among 

 plants Sponges are nowhere very abundant except 

 in the Cretaceous Strata, where some forms occur 

 much like existing tribes, and similarly furnished 

 with siliceous spicula, and in some cases with a net- 

 work of anastomozing fibres. 



Foraminifera. These minute cellular structures 

 occur perhaps in most of the limestones and clays, 

 but at present the greater number are quoted from 

 the Upper Mesozoic and Csenozoic Strata. In ge- 

 neral they correspond much and even remarkably to 

 existing kinds. Some fossil groups, extremely vari- 

 able in form, appear quite undistinguishable from 

 recent examples; so that by this tribe of animals 

 there appears a continuity of some specific forms 

 from Mesozoic through Csenozoic to recent times 1 . 



Zoophyta. The fossil groups are principally of 

 the kinds which secrete the stony support known as 

 Coral, and belong to the division of Zoantharia. 

 With hardly an exception (Gorgonia?) the numerous 



1 Carpenter, Proc. of Roy. Soc. 185560. Jones and Parker, 

 Journal of the Geological Society of London, 1860. 



