10 BRITISH FOSSIL CORALS. 



parts by a pellicular epitheca, which Mr. Searles Wood has designated by the name of 

 periostracum, and presents some slight transverse folds. In the parts where the epitheca 

 is worn off, the costm become visible. These are narrow, equal, closely set, and composed 

 of a single series of indistinct, obtuse granulae. The intercostal spaces present a series of 

 small mural perforations, disposed with some regularity. None of the numerous specimens 

 of this fossil which we have examined had the calice well preserved, and consequently 

 we have not been able to ascertain as yet whether its margin is crenulated or entire, the 

 fossula deep or shallow, and the columella projecting or not ; but it is evident that the 

 calice must be sub-circular, or slightly elliptic, with its two axes in the proportion of 

 100 : 120, and that the columella is spongy, not greatly developed, and spread in the 

 direction of the long axis of the calice. 



The septa are well developed, and always form five cycla, but do not appear ever to 

 constitute a sixth cyclum. The mode of arrangement of these lamina?, which is charac- 

 teristic in the family of Eupsammidse, is very evident in this species : the septa of the 

 first four cycla are straight, but those of the fifth cyclum deviate a great deal from the 

 direction of the radii of the circle represented by the calice, and are bent. In this last 

 cyclum the septa of the sixth order are placed very close to the primary septa, and are 

 united to them to a certain extent, near the wall, but diverge strongly from them as they 

 advance towards the centre of the visceral chamber, and join the ternary septa near the 

 columella ; those of the seventh order are disposed in the same way near the secondary 

 septa, and are also united to the ternary septa by their inner edge, but do not advance 

 quite so near the centre of the visceral chamber ; the septa of the eighth and ninth orders, 

 which complete the fifth cyclum, are smaller than the preceding ones, and are strongly 

 bent, so as to join the septa of the sixth and seventh orders ; and the septa of the fourth 

 and fifth orders, which constitute the fourth cyclum, remain free, and advance in the 

 middle of the sort of irregularly circular depressed area, formed by the coalescence of the 

 septa of the eighth and ninth orders with those of the sixth and seventh. All the septa 

 are very closely set and thin, but the primary and secondary ones enlarge a little towards 

 their inner edge, and are almost equally developed, so that the adult corallum assumes the 

 appearance of having twelve septal systems instead of six, which is the real number. We 

 must also add, that the laminee constituting all these septa are cribriform, and not very 

 granulate. 



The length of this corallum is commonly about eight lines, but the individual repre- 

 sented by fig. 3 is more than twice as tall, without being broader than usual. The calice 

 is in general about seven or eight lines broad in one direction, and six lines in the other. 



The greater development of the epi&eca might suffice to distinguish Balanopliyllia 

 calyculus from all the other species belonging to the same genus, but it differs also from 

 B. prcclonga} (a fossil species belonging to the Miocene deposits of Turin) by its broad basis, 



1 Turbinolia prcelonffa, Michelin, Icon., pi. ix, fig. 1. 



