chief Generic Types of Palceozoic Corals. 127 



simple, and their form is more or less conical and usually 

 curved. The epitheca is complete, sometimes thin, but in 

 other cases thick, with strong longitudinal strige. Minute en- 

 circling lines of growth are present, along with annulations of 

 growth. The calice is moderately deep, and the septa extend 

 nearly to the centre of the visceral chamber, apparently with- 

 out ever quite reaching it. Small secondary septa usually, 

 but by no means always, alternate with the primary septa. 

 As a general rule dissepiments are present, in the form of deli- 

 cate plates crossing the interseptal loculi ; but these are never 

 developed in such quantity as to form a distinct zone of vesi- 

 cular tissue exteriorly (PI. VIII. figs. 5 A, 6 A, 7 a). 



The tabulfe are always present, and are always well deve- 

 loped, thougli they do not possess the form of distinct, strong, 

 transverse plates. On the contrary, they form a series of 

 more or less irregular arched plates, with their convexities 

 upwards, which anastomose and become more or less freely 

 united with one another. They are not, however, confined to 

 the central area of the corallura, but reach the inner surface 

 of the wall (PI. VIII. figs. 6 & 7). 



The columella is invariably present, and is formed by a 

 cristiform or clavate prominence in each successive tabula. 

 It is thus not a true columella, as is sufficiently shown by 

 longitudinal sections (PI. VIII. figs. 6 & 7), where there is 

 simply a pseudo-columellarian line passing down the centre. 

 One extremity of this pseudo-columella is joined directly with 

 the septum occupying the septal fossette. Tlie other extremity 

 seems sometimes to be connected with the primary septum 

 directly opposite to the septal fossula ; but more commonly it 

 appears to be free, and no such connexion seems to be esta- 

 blished (PI. VIII. figs. 3 A-7 a). In L. hreve, De Kon., the 

 columellar prominence is said not even to have its usual con- 

 nexion with the septum in the fossula. Though well marked 

 in specimens exhibiting the interior of the calice, the septal 

 fossette is not a conspicuous object in transverse sections of 

 Lophophyllum, and is generally only recognizable by the fact 

 that the columellar eminence is prolonged into it. 



The genus Lophophyllum. agrees in many respects with 

 ZaphrentiSj more especially in the characters of the septa and 

 dissepiments. It is distinguished, however, from this by the 

 comparatively irregular tabulae, the different nature of the 

 fossula, and the presence of the central columellar eminence. 

 Almost the only genus with which LophopliyUuvi runs any 

 risk of being confounded is Gyathaxonia, Mich. ; but sections 

 at once show that it is fundamentally distinguished from the 

 latter by the possession of tabulie. In CyatJiaxonia^ also, 



