13 



BRITISH FOSSIL CORALS 



peduncle. The habit of the species resembles that of the majority of the stunted 

 Thecosmilia of the period. 



2. Thecosmilia mirabilis, Duncan. PI. II, figs. 10, 11. 



The corallum is short, very finely pedicellate, increasing rapidly in breadth, and 

 terminating by a large upper surface on which are several circular and distinct calices. 

 The trunk of the corallum is smooth, and is slightly marked with rounded transverse 

 swelhngs, and corresponding constrictions. No costse can be seen. The corallites are 

 unequal in size, separate immediately, do not increase by fissiparity, and are characterised 

 by circular calices having a very sharp margin. The calices are shallow. The septa are 

 numerous, crowded, and very regular ; they are alternately long and short, and all are 

 marked with small lateral swellings and faint linear depressions on the upper edge. 

 The largest cahces have four cycles of septa, and nearly a complete fifth cycle, the septa 

 numbering from seventy-six to eighty-four. 



Height of the corallum ^ths inch. Breadth of the upper surface ^ths inch. Dia- 

 meter of the largest calice ^ths inch. 



Locality. The Sutton Stone. In the Collection of Rev. H. Winwood, F.G.S., 

 Bath. 



3. Thecosmilia serialis, Duncan. PI. IV, figs, 10 — 1:2. 



The corallum has a narrow, curved, and rather long peduncle, which gives off several 

 corallites from its summit. 



The peduncle is strongly marked with lateral ridges and constrictions, and so are the 

 corallites. 



The epitheca is stout, and, where worn, permits the costse to be seen. 



The young corallites arising by fissiparity from the parent, which constitutes the 

 peduncle, separate into some which remain circular in transverse outline, and into others 

 which form short serial calices. 



The circular calices present four cycles of septa, and the serial have their septa less 

 crowded and larger. The serial calices do not present any evidences of fissiparity. 



Height of corallum inch. Diameter of circular calice 3th inch. Length of serial 

 calice ^ths inch. Breadth of serial calice T^th inch. 



Locality. The Sutton Stone. In the Collection of Charles Moore, Esq., F.G.S., Bath. 



This species belongs to the stunted Thecosmilice so characteristic of the Triassic and 

 Liassic coralliferous strata ; it is readily distinguished by the number of corallites spring- 

 ing from the peduncle, and by its long and serial calices being mixed with rounded ones. 



