GEOLOGY AND PALEONTOLOGY OP THE CANAL ZONE. 451 



Synapticulae in three or four vertical rows — in the outer portion of 

 the interseptal loculi, there may be even more. Very thin, nearly 

 horizontal dissepiments present. The wall is similar to that of 

 S. pliocenica, but thinner. 



Columella, papillary. The papillae are fine, more delicate than in 

 S . pliocenica. 



Locality and geologic occurrence. — Florida, station No. 3300, 

 Shell Creek, collected by F. Burns (type); station 2094, Caloosa- 

 hatchee River, Florida, collected by W. H. Dail; Pliocene. 



Type.— No. 325196, U.S.N.M. (pi. 119, figs. 1, la). 



Paratype.— No. 325195, U.S.N.M. 



This species is separated -from S. pliocenica by its generally more 

 delicate structure, more numerous septal dentations, and more 

 numerous septa. It differs from S. siderea (Ellis and Solander) by 

 its larger and shallower calices and its more numerous septa. 



The closely crowded, transversely compressed, and finely frosted 

 septal dentations of S. dalli give it an appearance very different 

 from any other American species of Siderastrea. The number of 

 septa is in corallites of the same diameter about the same as in 

 specimens of S. silecensis. 



11. SIDERASTREA CONFERTA (Duncan). 



Plate 117, fig. 3; plate 120, figs. 1, 2, 2a, 3, 4; plate 121, figs. 1, la, 2, 2a. 



1863. Isastraea conferta Duncan, Geol. Soc. London Quart. Journ., vol. 19, p. 422, 



pi. 14, fig! 2. 

 1867. Isastraea conferta Duncan, Geol. Soc. London Quart. Journ., vol. 24, p. 25. 



The original description of Isastraea conferta is as follows: " Coral- 

 lites very close, tall, slender, straight, and prismatic; a transverse 

 section shows the wall to be very thin. The breadth of the corallites 

 varies from three-tenths to one-tenth inch [ = 7.5 to 2.5 mm.]. 

 Septa very numerous; linear; the primary extend to the centre of 

 the corallite, the secondary less so, and the others join the larger 

 septa at a very acute angle; all are very slender and excessively 

 crowded. There are eighty-two septa in the larger corallites, sixty 

 in the smaller. The septa of one corallite do not join those of the 

 next, but end sharply at the wall. Endotheca plainly exists, linear, 

 appearing, in transverse section, to divide the interseptal loculi 

 into several cells. The reproduction is by submarginal budding. 

 The sclerenchyma has been replaced by dark homogeneous silica, 

 and the interspaces by porcellanous and opaline silica. 



"From the Chert-formation of Antigua. Coll. Geol. Soc. 



"This is a very remarkable form. Unfortunately no calices exist; 

 but the transverse view of the corallites is excellent. If the specimen 



