of tin .liit/iozod Tabulafd. 5 



tlit'ir predecessors, one beneiith tlio other, like so niany in- 

 verted I'uiiiiels. It was rcecntly pointed out to me by (J. Kisen 

 that there are hirge speeiineiis i'ouud in CJothiud eomhininj^ 

 tlie peeuliar features of Lab^'diid with those of ('<rnostroin(i] so, 

 perhaps, there may also be reason to eliminate the hitter from 

 the Anthozoa. 



Next we have to consider a f:freat variety of otlier fossils 

 which are geiu-rally stated to be Tabulata, but which in reality 

 ;u'e Bryozoa. Foremost stands the nvnus MnnticuUpord. If 

 numerous s])ccimens of the common Silurian M. pelrupoUtana^ 

 Pand., be closely scrutinized, it will be seen that its senii- 

 fflobose colony, so closely resembling a Facosltes in its initial 

 aevelopment, has an ori<i,in that could hardly be suspected. 

 It be<j^ins, indeed, as a Bryozoon, as a Discoporella, as what 

 Hall has termed Ceramopora iinhricata (Pal. N. Y. vol. ii. 

 J). 1()9, J)!. 40 E. fiL!;s. 1 rt-1 i). 'J'herc can be no doubt that 

 this is closely allied to the recent Discoporeila (see Fr. Sinitt, 

 (Efvers.Vet. Akad, Fiirhand. 1866, p. 476, pi. xi. %. 4). The 

 basal surface of a Movticuli'pora, when the epitheca is very 

 thin, clearly shows that it is in its first origin a Ceramopora. 

 The smallest Ceramopora' which I have hitherto seen consist 

 of a thin circular disk with elevated edges. From the smooth 

 centre of the superior surface four or five wedge-shaped zoa'cia 

 radiate outwards, each of a length of 4- raillim., their mouths 

 being oblique, with the inferior lip somewhat protracted. On 

 both sides of the mouth there is a short, pointed spine. In its 

 interior such a zo<eeium is transversely divided by some irre- 

 gular tabula?. The interstitial ribs, which are so characteristic 

 of the Discoporellida?, are also distinctly seen between the 

 zocecia of Ceramopora. New zooccia are budded forth in quin- 

 cunx from the corners of the old zocecia ; and in the periphery 

 of the colony they become more crowded, having the mouth 

 oval and erected. In the interstices is seen what might be 

 taken to be a coenenchyma ; but this in reality is composed of 

 nothing but smaller irregular zocecia. When the colony has 

 spread out laterally, there are seen at the sides of the first 

 smooth centrum several others regularly distributed on the 

 surface, from which zooecia radiate, just as if the disk were 

 composed of an aggregation of coalescent initial buds. When 

 the colony has thus gained the expanse of an inch or more, 

 the zooccia grow vertically upwards ; and the colony by-and- 

 by assumes a semiglol)ular shape, and is converted into a 

 MoaticuUpora. All the zooecia are then tubular, their mouths 

 quite circular, and armed with a pair of very short spines, their 

 size varying in different cases. The larger zocecia have around 

 them either an enq^t}- space or^ as above stated, a cellular 



