Appendix to Part I. 185 



Fenestella and the meshes of the ' inner ' net-work. Similar con- 

 formities are admirably shown in Mr. Phillips's excellent figures 

 (< Pal. Foss.' pi. xiii. f. 38). 



The solid portions of the structure being exceedingly fine, resem- 

 bling the thread of the most delicate lace, attempts to discover satis- 

 factorily internal characters proved unsuccessful, except in one place, 

 where a true cellular arrangement was believed to be visible. 1 

 Of the nature of the investing crust, nothing also has been deter- 

 mined. 



Though the name Hemitrypa may be objectionable, as applied 

 to the corals under consideration, it has been thought right to re- 

 tain the word, until the full characters of the genus shall have 

 been ascertained. 



Falmouth, January 1844. 



1 A Codrington lens, half-an-inch in diameter, was invariably 

 used in examining the corals described in this notice. 



