68 BRITISH FOSSIL CORALS. 



only by characters of secondary value, which agree, however, very well with those of the 

 other Corals belonging to the same generical division. Septa forming four complete cycla ; 

 exsert, thick exteriorly, but thin inwardly, and presenting but few granulations on their 

 lateral surfaces. Those of the second cyclum almost as large as the primary ones ; the 

 tertiary ones but little developed, although they correspond to large costae, and not as tall 

 as those of the last cyclum, which are grouped very closely on each side of the primary and 

 secondary ones. Height of the corallum, one inch two or three lines ; great diameter of 

 the calice, six or seven lines. 



The genus Bathycyathus contains two other species, which are both recent : B. Chilensis 1 

 and B. Indicus? which differ from B. Sowerbyi in having an additional cyclum of septa, 

 the calice arched, and the costae more developed near the basis. We have seen but two 

 specimens of this fossil; one, belonging to the collection of Mr. D. Sharpe, is catalogued 

 as having been found in the Gault near Folkstone ; the second, belonging to the museum 

 of the Geological Society, is referred with doubt to the upper greensand of Kidge, in 

 Wiltshire. 



Family ASTREIDtE (p. xxiii). 

 Tribe EUSMILIN^E (p. xxiii). 



1. Genus Trochosmilia (p. xxiv). 



Trochosmilia sulcata. Tab. XI, fig. 6, 6 a, 6 b. 



Corallum simple, turbinate, straight, tall, much compressed, subpedicellate, and ap- 

 pearing to be free. Wall presenting on each side two deep longitudinal furrows. Costa 

 distinct from the basis, slightly prominent, closely set, and unequal, especially towards their 

 upper end. Calice elliptical, sublobulated, and slightly arched ; its long and short axis in 

 the proportion of 100 : 200. Fossula very narrow, elongated, and not very deep. No 

 columella. Septa forming four cycla or more, rather unequal, closely set, thin, and slightly 

 exsert. Dissepiments not numerous. Height of the corallum, nearly one inch ; diameter 

 of the calice, six or seven lines by three ; depth of the fossula, two lines and a half. 



We have seen but one specimen of this fossil, which, although somewhat weather-worn, 

 appeared sufficiently distinct from all other species to authorise us in giving it a peculiar 

 specific name. It differs from Trochosmilia didyma 3 by its calice being straight, and not 



1 See our Monograph, of Turbinolidse, tab. ix, fig. 5. 



2 Loc. cit., tab. ix, fig. 4. 



3 Turbinolia didyma, Golclfuss, Petref, Germ., vol. i, tab. xt, fig. 11. 



