FAMILIES AND GEI^^ERA OF THE MADEEPORARIA. 



81 



of most Thecosmilians were simple forms r esemblmg MontUvaltice, 

 and growth proceeded for some time without increase, or the 

 reverse happened. The increase was clearly not invariably by 

 fissiparity of the parent ; subdivision and upward growth from 

 more than two centres may be noticed ; and the method is 

 indistinguishable from the results of gemmation. As growth 

 proceeded the calice either remained unaltered, or fissiparity, or 

 even something like serial growth, developed. 



The result in these last two instances was to produce calices 

 as varied in shape as in Mussa and SympJiyllla. 



Mr. Tomes, F.G.S., has introduced the genus Cliorisastrcea, E. 

 de Promentel, to absorb the Thecosmilics which grow at first by 

 budding and then by fissiparity. In his essay on the Lower-Oolite 

 Madreporaria (Quart. Journ. Greol. Soc. vol. xxxviii. p. 428, 1882), 

 the diagnosis of Cliorisastrcea is not introduced. A figure is given 

 of CJiorisastraea gregaria on plate xviii. figs. 1-3, the Thecosmilia 

 gr eg aria of Ed. & H., and M' Coy's Montlivaltia gregaria. 



The figure, however, does not represent the characteristic groove 

 or deep space between the walls of adjoining calices, which is the 

 special generic character of CJio?HsastrcBa according to the founder 

 of the genus, M. de Eromentel. Chorisastrcea will be considered 

 in its proper place. 



Genus Thecosmilia, Milne-Edwards and Jules Haime^ Hist, Nat, 

 des Corall. vol. ii. p. 354 (1857). 



This colony is usually csespitose, but sometimes becomes sub- 

 massive, expanding at the top in consequence of the more or 

 less complete union of a certain number of corallites together. 

 Usually the corallites tend to isolate rapidly by and after fissi- 

 parity, and their base develops but little with age. The cali- 

 cular margins are irregular. The columella is rudimentary or 

 none. The septa are strong, more or less exsert, regularly den- 

 tate above and granular laterally. The endotheca is well deve- 

 loped, and the epitheca is stout and strongly folded and reaches 

 close to the calices. Growth by fissiparity and rapid isolation, 

 or by gemmation and subsequent fissiparity. 



Distribution. — Fossil. Trias, Jurassic, Cretaceous, Tertiary : 

 Europe. Jurassic : England. 



Subgenus Cladophyllia, (genus) Milne-JEdwards Jules Uaime, 

 Hist. Nat. des Corall. vol. ii. p. 363 (1857). 

 Colony in the form of csespitose tufts. Corallites elongate, 



linn. JOUEN. ZOOLOGY, TOL. XVIII. 6 



