TABULATA. 



201 



(fig. 90), composed of closely approximated corallites, des- 

 titute of septa, provided with well-developed tabulae, and 

 differing from the Favositidce chiefly in the fact that the 

 walls of the corallites are imperf orate. Though ranging from 



Fig. 88. a, Fragment of Alveolites ramulosa, of the natural size ; 1>, Portion of the same 

 enlarged, showing the calices ; c, Fragment of Alveolites Billimjsi, of the natural size. 

 Devonian. (Original.) 



. 



the Lower Silurian to the Permian, inclusive, we have no 

 Mesozoic or Tertiary representatives of this family, so far as 

 is certainly known. Though 

 presenting a striking general 

 resemblance to the Farositidcc, 

 it is very doubtful if any close 

 relationship exists between the 

 Chcetetidce and the former. The 

 family, indeed, may possibly be 

 really Alcyonarian, though at 

 present the evidence would 

 rather point to its ultimate 



removal to the Polyzoa. At any rate, it should be remem- 

 bered that we have Mesozoic, Tertiary, and Eecent Polyzoa 

 (such as Heteropora), which can hardly be distinguished from 

 the Chcetetidce except by their not possessing tabulae. 



The chief genus of this family is Chcetetes itself (pro- 

 visionally including under this name the forms known by 

 the name of Monticulipora) ; and it is widely represented 



Fig. 89. Fragment of Striatopora flexu- 

 osa of the natural size, and two calices 

 enlarged. Upper Silurian. (After Hall.) 



