GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 447 



in no noteworthy character from typical S. siderea. One specimen 

 from this locality is 187 mm. across. 



Localities and geologic occurrence. — Miocene: Jamaica, Bowden 

 marl, received from Hon. T. H. Aldrich. Santo Domingo, Rio Cana, 

 Zone H, collected by Miss C. J. Maury. Cuba, La Cruz marl, 

 station 3446, near Santiago, collected by T. W. Vaughan. 



Pleistocene: Canal Zone, at station 5849, Mount Hope; and Costa 

 Rica, station 6251, Monkey Point, collected by D. F. MacDonald; 

 Moin Hill, Costa Pica, collected by H. Pittier. 



This species is general in the Pleistocene and living reefs of the 

 West Indies, eastern Central America, and Florida. 



The stratigraphic range of S. siderea is from the horizon of the 

 Bowden marl to the present. 



8a. SIDERASTREA SIDEREA var. DOMINICENSIS, new variety. 



Plate 114, figs. 4, 4«. 



This variety differs from typical S. siderea by having much larger 

 calices, which are as much as 6 mm. in diameter in a nearly hexagonal 

 calice, and 4.5 by 8 mm. in diameter in a much deformed calice; and 

 corresponding to the greater size of the calices, there are many quinary 

 septa. Otherwise there seems to be no important difference, for the 

 septal slopes, the septal dentations, the columellar pit, and the 

 papillary columella are about normal. 



S. siderea var. dominicensis resembles S. conferta (Duncan) in 

 possessing more than 4 cycles of septa, but according to the size of the 

 calices the septa of S. conferta are more numerous, more crowded, 

 and have more finely dentate septal edges; and the calices of S. 

 conferta are shallower and more open. 



Locality and geologic occurrence. — Haiti, living, collected by Lang- 

 ston, no more definite information. 



Type.— No. 36909, U.S.N.M. 



9. SIDERASTREA SILECENSIS, new species. 



Plate 116, figs. 1, la, 2, 3; plate 117, figs. 1, la, 16; plate 118, figs. 1, la. 

 1915. Siderastrea silecensis.Y attghan , nomen. nudum, U. S. Nat. Mus. Bull. 90, p. 18. 



The following is a description of the type of the species (pi. 116, 

 figs. 1, la): * 



Corallum massive, with domed upper surface. Greater diameter 

 of specimen 170 mm.; lesser diameter 140 mm.; thickness, originally 

 more than 85 mm. 



Calices polygonal, separating wall usually slightly raised. The 

 peripheral part of the septal margins is flattened, producing between 

 adjacent calicular fossae a flat area which ranges from 0.5 to 1.5 mm. 

 in width. Diameter of an adult calice, measured between the thecal 



