198 THE GENUS MONTICULIPORA. 



averaeine i-iooth inch in diameter. At first thin -walled, 

 they rapidly have their cavities contracted by a secondary 

 deposit of sclerenchyma. When viewed in tangential sections 

 (fig. 41, A and b), the visceral chambers of the corallites thus 

 appear to be oval ; but the original independence of the coral- 

 lites is shown by the persistence of the pentagonal boundary 

 lines between adjoining tubes, occupying the middle line of 

 the thickened wall. In these sections the visceral chambers 

 are sometimes encroached upon by a single blunt tooth-like 

 projection on one side ; but I can give no precise explanation 

 of this phenomenon. There is no appearance of any intersti- 

 tial series of tubes between the ordinary corallites, nor are any 

 " spiniform corallites " present. Tabulce, as seen in long sec- 

 tions, are few in number, sometimes apparently wanting, but, 

 when developed, always complete and horizontal, and often 

 placed at the same level in adjoining tubes, and thus marking 

 stages of growth. 



Horizon and Locality. — Cincinnati Group, Cincinnati, Ohio, 



Monticulipora (Monotrypa) briarea, Nicholson. 



(PI. 11. figs. 5-5^.) 



Chcektcs hriareus, Nicholson, Pal. Ohio, vol. ii. p. 202, PI. XXI. figs. 13-13/^, 

 1875. 



Spec. Char. — Corallum free (?), commencing in a pointed 

 base, which does not show any indication of having been at 

 any time attached to any foreign body. Above the base the 

 corallum expands, so as to form an inverted and compressed 

 cone, from the summit of which proceed a variable number of 

 cylindrical branches, generally from two and a half to four lines 

 in diameter, the final terminations of which are unknown, 

 though they may branch more than once. The surface is 

 smooth, without monticules, the calices being oval or circular, 

 mostly about i-8oth inch in diameter, not separated (so far as 

 observed) by any small interstitial tubes. The corallites are 



