﻿GEOLOGY AND PALEOXTOLOGY OF THE CANAL ZONE. 367 



Eiidothecal dissepiments delicate, thin, nearly horizontal, slightly 

 inclined do^^^lward from the corallite walls. In this series of speci- 

 mens the corallite walls are thick and close together, those of ad- 

 jacent coraUies sometimes being solidly fused together; usually, 

 however, there is some exotheca, consisting of stout, subhorizontal 

 dissepiments. 



Columella well developed, formed by interlacing processes from 

 the inner edges of the septa; diameter from one-tliird to one-half 

 that of tlie calice; its upper sm'fcce about 1 mm. below the thecal 

 margin. 



These specimens, it should be repeated, are typical, and except in 

 size and to a certain extent in the configm'ation of the surface show 

 almost no variation. They come from the follovving localities: Dry 

 Tortugas, Florida, Dr. Edward Palmer, collector, 8 specimens; east 

 end of Hog Island, Bahamas, B. A, Bean, collector, 1 specimen; 

 Florida and the Bahamas, many specimens, collected by T. W. 

 Yaughan and others. There are other specimens, bearing the in- 

 definite label ''West Indies" or having no locality stated. These 

 localities indicate that the species in its typical foim is of general 

 occurrence in the coral reef areas around the Caribbean Sea and Guli 

 «f Mexico. 



The recent specimens in the United States National Museum show 

 at least fom' kinds of variation from the typical form. 



Variation No. 1 (pi. 84, fig. 2). — This variation is, I believe, only 

 a gi'owth form. It, in its structural featm-es, is the same as the 

 typical form, except that the septa near the growing edge are less 

 exsert and the exotheca appears to be absolutely solid. The coraUum 

 is an obtuse, compressed column, with an undulated surface. Greater 

 diameter of the base, 62 mm.; lesser 52 mm.; height 72 mm. 



Locality . —Tfry Tortugas, Florida. 



Variation No. 2 (pi. 81, fig. 2). — The general growth form is similar 

 to that of tjqjical specimens, except that the surface is thrown iiito 

 gibbosities of irregular shape and size; these are often about a centi- 

 meter in height and several centimeters in diameter. The caUces 

 are larger than in the typical specimens, often measuring 3, occa- 

 sionaU}?^ 4 millimeters in diameter, between thecal summits. The 

 thecal edges are slightly elevated ; the margins of the primaries and 

 secondaries decidedly exsert, not mfrequently standing 2 mm. above 

 the intercoraUite furrow. The three characters here mentioned are 

 the distinguishmg ones of this variation, namely, gibbosities on the 

 surface; larger calices; and more exsert septa. 



Localities. — Dry Tortugas, Florida, Dr. Edward Palmer, collector, 

 1 specimen; east end of Hog Island, Bahamas, B. A. Bean, collector. 

 1 specimen; and two other specimens, mthout locality lab<'ls. 



