ZAPHRENTOIDEA. 



293 



Axophyllum, again, comprises simple Clisiophylloid corals of Car- 

 boniferous age, in which there is a large vesicular pseudocolumella 

 piercing a central tabulate area, which is enclosed by an accessor}- wall, 

 and is in turn surrounded by a vesicular zone. Lastly, we may include 

 here the Carboniferous genus Lo?isdaleia (fig. 134), in which there is a 

 composite, fasciculate, or astraeiform corallum. Each corallite has, as 

 usual in this family, a large pseudocolumella, formed of twisted lamellse, 

 and having a vesicular structure (fig. 171, a). The columella traverses a 

 well-developed tabulate area, but the genus differs from the other types 

 of the family in the fact that the outer zone of the corallum is occupied 

 wholly by large lenticular vesicles, the septa being here obsolete, and 

 being developed in the central region only. In the series of the Clisio- 

 phyllidce, Lonsdaleia holds the place occupied by Lithostrotion in the 

 series of the CyathophyllidcE. 



II. Zaphrentoidea. 



The section of the Zaphre?itoidea comprises those Rugose Corals 

 in which there is a comparatively limited amount of dissepimental 

 endotheca, the visceral chamber never being sheathed with a zone 



Fig. 172.— Morphology of Zaphrentis. A, Transverse section of a fully-grown individual of 

 Zaphrentis Enniskilleni, from the Carboniferous Limestone, enlarged about twice, b, Trans- 

 verse section of a very young example of the same, enlarged six times, c, Part of the theca of 

 the same, enlarged, showing one long and two short septa, the bases of these structures forming 

 the wall. The septa have a primordial lamina thickened by stereoplasma. d, Long section of 

 the same, showing the tabula?. (Original.) 



of vesicular tissue ; while there is, on the other hand, a proportion- 

 ately extensive development of the tabulae. [In the Hadrophyllidce 



