GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 389 



This species in its general aspect resembles Oyathomorpha helli 

 Vaughan (see p. 459), but has thinner septa and costae and deeper 

 calices. The lower surface is more or less invested with epitheca, 

 and no synapticulae could be found. 



10. ORBICELLA CANALIS, new species. 



Plate 94, figs. 1, lo, 2, 2a, 3, 3«; plate 97, figs. 4, 4«. 



This species can best be characterized in terms of com])arison with 

 O. costata. The growth forms and the general facies of both are 

 similar, except that the maximum size of the calices in 0. canalis 

 is nearly the minimum size in 0. costata: range in calicular diameter 

 of 0. canalis from 5 to 9 mm., average about 6 or 6.5 mm. 



The costae in 0. canalis are alternately large and small or sub- 

 equal around the cahcular edge below which they may be subequal, 

 alternately large and small, or the last cycle may disappear. 



Septa in 4 or nearly 4 cycles; primaries notably larger than the 

 secondaries except in occasional unusually large calices, and each 

 bears a strong tooth on its inner end; secondaries thinner than the 

 primaries, also with a tooth on the inner end, these and the primaries 

 reach the columella; tertiaries shorter, but with a paliform thickening 

 or a tooth on the inner end; quaternaries decidedly small. The 

 septa usually are lanceolately thickened in the wall, in this character 

 resembling typical 0. costata. 



The columella is formed by the fusion of the inner ends of the 

 septa and is less developed than in 0. costata. 



Endothecal dissepiments well developed, thin, from 0.5 to 1.5 mm. 

 apart. Exotheca consists of thick-walled blister-like, small vesicles, 

 about 0.5 mm. high, and more or less wavy platforms which extend 

 between the corallites. 



Localities and geologic occurrence. — Canal Zone stations 6015 and 

 6016, quarries in the Emperador limestone. Empire, collected by 

 T. W. Vaughan and D. F. MacDonald, also collected in Empire by 

 Ralph Arnold. 



Anguilla, stations 6894, lower bed; 6966, middle bed, between 

 50 and 75 feet above the base of the section; and 6967, upper bed, 

 west side of Crocus Bay, collected by T. W. Vaughan. 



Type.—^o. 324862, U.S.N.M. (pL 94, figs. 1, la). • 



Paraty pes. —No. 324861, U.S.N.M. (pi. 94, figs. 2, 2a; pi. 97, figs. 4, 

 4a). The specimen represented by plate 94, fig. 3, 3a No. 324859, 

 U.S.N.M. is a varietal form that appears referable to 0. canalis; it is 

 from Anguilla. 



Orbicella canalis is so nearly related to a number of Antillean upper 

 Oligocene species, that I have hesitated to appl}^ a distinctive name, 

 but as the large suite of specimens before me, 30 of those from Em- 

 pire, Canal Zone, have been selected as the reserve series of the 

 United States National Museum, shows characters by which they 



