PROBLEM OF THE MONTICULIPOROIDEA 1 63 



region. The axial cells overlap so as to be three or more deep 

 in transverse section. The peripheral region is characterized by 

 filled interspaces or mesopores which more or less completely 

 separate the cells, the cell margins rising a little above the inter- 

 space at the surface. Zoarial growth as to cell increase took 

 place only axially, i. e., at the branch ends. The peripheral 

 growth comprised thickening of the branches with cell lengthen- 

 ing on the obverse side and with about equally as thick, solid or 

 rarely vesiculose increment on the reverse side, thus proving the 

 branch to have been surrounded by a secreting cortex. Young 

 branches usually have on the obverse a median keel, the edge of 

 a wall or walls extending from the mesial line, and this E. O. 

 Ulrich compares to the longitudinal ridges dividing cell rows in 

 Rliinidictya. It bears a few acanthopores. An obtuse keel on 

 the reverse produces no internal wall distinction. With age the 

 keels disappear from the then rounded or flattened obverse and 

 reverse sides, and the fenestrules constrict, even closing some of 

 them. Branches are 1 to 2 mm thick. 



The cell apertures are arranged in one or two rows on each 

 side of the median keel, or a few more at inosculations. 



The basal expansion is the key to the better understanding 

 of this zoarium. To the description of it as " an expanded base," 

 the following is added from specimens at hand : Basal expansion 

 thin, incrusting, about 2 or 3 cm in diameter, the marginal or 

 younger part bearing stellate monticules like those of Stellipora 

 i^Constellarid) , i. e.,a. central depressed macula with six to twelve 

 rays, between which are as many sloping ridges of autocells. 

 These monticules or stars are about 3 mm in diameter. The rest 

 of the expansion is crowded with young stars between larger 

 older ones of various sizes. It appears that the stars increase in 

 size by addition of a few ridges, all of the ridges elevating rap- 

 idly at their proximate ends. When about i mm high they begin 

 to anastimose, and they continue to grow and elongate upward, 

 anastimosing and branching, whence arises the reticulate funnel- 

 shaped frond, with cell apertures turned to the outside and a 

 solid, striate surface on the inner side ; the obverse side of the 



