FISTULIPORIDiE. 



357 



Mesopores are not developed, but there are usually numerous acantho- 

 pores (fig. 232, A and b). The tabulae are usually straight and complete, 

 but they are sometimes perforated by central apertures (fig. 232, c). The 

 walls of the autopores in Stcnopora have been described as being per- 

 forated by mural pores, but, as previously noted, the researches of 



Fig. 232. — Sections of Stcnopora Hoiusii, from the Carboniferous rocks of England, enlarged 

 about eighteen times. A and b, Tangential sections ; c, Longitudinal section, showing Ihe 

 periodic thickenings of the walls of the tubes. (Original.) 



Waagen and Wentzel have rendered it certain that the supposed mural 

 pores must be otherwise explained, and that the walls of the tubes are 

 really imperforate. 



FlSTULIPORID^E. 



The skeleton in this family is of very variable form, and is com- 

 posed of large tubes (" autopores ") which are in general more or 

 less completely isolated (fig. 233) by the development of a copious 

 series of smaller tubes (" mesopores "), these latter being often 

 aggregated into star-shaped groups or "maculae," which serve as 

 centres of growth for the colony. The walls of the autopores are 

 either completely unthickened (Callofiora and Prasopora), or are 

 specially thickened on one side (Fistulipora). The mesopores are 

 furnished with more numerous tabulae than the autopores ; and in 

 some cases {Fishdipord) their walls are incomplete, thus allowing 

 their tabulae to coalesce so as to form an interstitial tissue of lentic- 

 ular vesicles. The mode of increase as regards the autopores is 

 typically by " ccenenchymal gemmation," the mesopores increasing 

 by means of fission. Pseudoseptal spines are occasionally devel- 

 oped, and pseudoseptal folds are commonly present. Acanthopores 

 are occasionally, but not usually, developed. 



