FROM THE GREAT OOLITE, 187 



media of Eeuss, from the Cretaceous deposits of Gosau, is a good 

 illustration of this. When the corallum of Orosens has been ground 

 down and polished, the intimate connection of the calicos with the 

 costae forming the supposed ridges becomes even more evident, and 

 the importance of the successive development of the calicos in lines 

 still more obvious. 



CoMosERTs vERMicuLARis, M.-Edw.aud Haime, Brit. Foss. Cor. p. 122. 



Meandrina vermicular is, M'Coy, Ann. & Mag. Nat. Hist. ser. ii. 

 vol. ii. p. 402. 



Several very small examples of this species, associated with 

 larger ones, have been met with on Parley Down, which have a 

 very leaf-like form with a thin edge. On these the ridges are 

 especially pronounced, and the costse, which meet on their line of 

 greater prominence, are rarely continuous. 



Oroseris Slatteri, Tomes. 



A considerable number of specimens of a species of Oroseris, 

 which, though varj'ing extremely in form, may nevertheless be 

 referred to the above species, have been met with at Combe Down, 

 Hampton Down, and Farley Down. Those on Hampton Down are 

 in large blocks of stone, and are of great size, but they are very ill- 

 preserved. The Farley-Down specimens are, however, in a far 

 better condition, and as they occur of all sizes, they furnish a good 

 opportunity of studying the successive periods of growth, and illus- 

 trate the particular mode of increase of the genus. Young examples 

 are simple, and usually, but not invariably, turbinate. The calice 

 is circular and not very deep. At this period they greatly resemble 

 Thecoseris. At a more advanced stage the calice has become elon- 

 gate, and it has two or three calicos in a line. But it still retains 

 its turbinate form, though it speedily afterwards departs from the 

 upward mode of growth and spreads out in all directions, eventually 

 attaining to a great size and undefinable form. 



I am in complete ignorance of the early form and mode of growth 

 of such species of Oroseris as are broadly attached or incrusting, 

 but I may venture to record my conviction that none of them ex- 

 hibit the same method of growth as Comoseris, 



GeAus Trictcloseris, Tomes. 



M. Pratz, in his very valuable paper on the Fungidae, published 

 in the 29th volume of the ' Palseontographica ' (1882), suggests that 

 the specimen from which I drew up my description of the genus 

 may be nothing more than a young example of a species apper- 

 taining to some other genus. Of the more recently described 

 species from the Great Oolite of Fairford, Tricydoseris Umax, he 

 entertains the same opinion, and informs me that there are many 

 examples in the museum at Munich which have considerable re- 

 semblance to the specimens I have figured. When drawing up the 

 description of Tricydoseris Umax I made use of many young sped- 



