198 The Ohio Journal of Science [Vol. XVII, No. 6, 



the tabulae, and the tendency of even the longer septa to ter- 

 minate before reaching the center of the corallum. The fre- 

 quency with which the proximal free margins of the longer 

 septa show evidence of twisting or contortion, even when not 

 reaching the center of the corallum, is another characteristic 

 feature. 



Acervularia (?) paveyi, sp. nov. Plate X, Fig. 10. 

 Corallites forming astraeiform colonies 12 centimeters or more in 

 diameter. Corallites polygonal, usually more or less six-sided, the 

 transverse diameters varying from 13 to 20 millimeters, with 15 milli- 

 meters as a fair average. The walls are thin and distinctly defined. 

 The central part of the calice appears to be surrounded by a cylindrical 

 wall varying from 6 to 10 millimeters in diameter, with 7 or 8 millimeters 

 as a fair average. In general, the cylindrical walls are situated about 

 half way between the center of the calice and the middle part of the 

 surrounding polygonal walls. Between 45 and 50 septa extend from 

 the polygonal walls toward the central part of the calice; of these 

 practically all appear to pass into the space within the cylindrical wall 

 although "only a part reach the center of the calice. The septa are con- 

 nected" by dissepiments in the spaces both within and without the 

 cylindrical wall. In the specimen here figured, dissepiments are_ clearly 

 preserved within several of the circular spaces included by the cylindrical 

 walls, but are much less satisfactorily indicated in the exterior part 

 of the corallites, between the central cylindrical wall and the outer 

 polygonal wall. In none of the corallites is there any evidence of 

 horizontal tabulae within the central space enclosed within the cylindri- 

 cal wall. In one of the corallites there apparently is evidence of 

 horizontal tabulae resting on vesicular tissue, but in all of the other 

 corallites there is no clear evidence of the presence of tabulae. 



From Strombodes, the species here described is readily dis- 

 tinguished by the conspicuous development of septa extending 

 vertically throughout the corallites and the absence of numerous 

 infundibuliform tabulae, resting on a conspicuous vesicular tis- 

 sue. From true Acervularia, it differs in the absence of numer- 

 ous tabula within the central area, enclosed by the cylindrical 

 wall. The continuation of the septa from the exterior prismatic 

 wahs of the coralHtes to within the space enclosed by the 

 central, cylindrical wall, indicates that the structure of the latter 

 needs further elucidation, but this apparently can not be fur- 

 nished by the silicified specimen at hand. From Prisma- 

 tophyllum, it differs in the presence of the central cylindrical 

 wall, and in the absence of numerous tabulae within the central 

 cylindrical part of the corallites. 



