GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 385 



10 mm. Type in the Geological Society of London; duplicate in the 

 United States National Museum (No. 155276). The preceding re- 

 marks are based on the latter. 



Localities and geologic occurrence. — Type said to come from the 

 Nivaje shale of Santo Domingo. 



Costa Rica, station 4269, Port Limon; collected by Doctor Wailes 

 in a bed of reputed Pliocene age. The size of the ealices, and the 

 costae, wall, and columella of the Port Limon specimen are as in var. 

 endothecata; but usually every other septum meets the columella; a 

 cycle of small septa between the larger is clearly present. As it is 

 probable that the last cycle of septa has been destroyed in the type of 

 var. endothecata, the presence of small septa between the larger would 

 not indicate specific difference. The strongly developed costae with 

 small ones between them are the same in both the type and the Port 

 Limon specimens. 



The stratigraphic range of this variety, therefore, is from the 

 Nivaje shale (lower Miocene) to probably Pliocene. 



6b. OEB1CELLA CAVERNOSA var. CYLINDRICA (Duncan). 



Plate 89, fig. 2. 



1863. Astraea cylindrica Duncan, Geol. Soc. London Quart. Journ., vol. 19, p. 



434, pi. 15, fig. 8. 

 1868. Heliastraea cylindrica Duncan, Geol. Soc. London Quart. Journ., vol. 24, 



p. 24. 



This variety closely resembles var. endothecata. It has smaller 

 corallites, 5 to 6 mm. in diameter; fewer septa, 12 to 16 principal 

 septa, with from 1 to 3 smaller intermediate septa. Between each 

 pair of larger septa on the mural summits around the ealices is an 

 intermediate rudimentary septum; the total number of septa is 

 about 38. The costae corresponding to the principal septa are 

 strikingly prominent, while those corresponding to the rudimentary 

 septa are very small or even obsolete. The calice is rather deep, 

 about 2.5 mm. 



This coral may be only a growth facies of 0. endothecata. 



Localities and geologic occurrence. — Duncan type, in the Geological 

 Society of London, comes from "the tufaceous limestone" of Santo 

 Domingo; duplicate specimen No. 155277, U.S.N.M. Miss C. J. 

 Maury has recently collected the variety in Santo Domingo as fol- 

 lows: 



Rio Gurabo, zone D, associated with Stylophora affinis Duncan, 

 Madracis decaciis (Lyman), Pocillopora crassoramosa Duncan, 

 Siephanocoenia intersepta (Esper), Orbicella limbata (Duncan), Orbi- 

 cella, cavernosa (Linnaeus) var., Syzygophyllia dentata (Duncan), 

 The single specimen collected is essentially typical, in fact it is a 

 better specimen than Duncan's type. Cercado de Mao, without 



