GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 431 



they are thick and subequal, within the calice there is indefinite alter- 

 nation in size, and there may be irregular grouping, but usually the 

 small septa do not fuse to the sides of the larger. The septal margins 

 within the calices fall steeply to the bottom of the relatively large 

 fossa. 



Septo-costae continuous from one calice to the next; they are low, 

 subequal, and synapticulae are visible between them. 



Columella formed by the fusion of the inner ends of the long septa; 

 it is styliform in many calices, and in some it is distinctly compressed. 



A specimen from station 6016, represented by plate 110, figures 

 3, 3a, is intermediate in its septal and septo-costal characters between 

 the two other specimens above described. 



Localities and geologic occurrence. — Canal Zone, stations 6015 and 

 6016, in the Emperador limestone, quarry, Empire, collected by 

 T. W. Vaughan and D. F. MacDonald. 



Cotypes — Nos. 325232, 325334, 325335, U.S.N.M. 



This species has its nearest relative in the living P. clivosa, from 

 Pearl Island, Bay of Panama. 



Genus LEPTOSERIS Milne Edwards and Haime. 



1849. Leptoseris Milne Edwards and Haime, Comptes Rend., vol. 29, p. 72. 

 Type-species. — Leptoseris fragilis Milne Edwards and Haime. 



LEPTOSERIS PORTORICENSIS, new species. 



Plate 107, figs. 2, 2a, 26. 



Corallum forming a rather thick unifacial frond. The type-speci- 

 men is a fragment and does not give a definite idea of the size to 

 which the corallum grew. It is 45 mm. long, of the same width, 

 and 5.5 mm. thick. The back is without calices; it is naked and finely 

 costate, about 23 costae to 1 cm. The costae are subequal in size, 

 alternately larger and smaller, or every fourth may be slightly larger 

 than those intervening. The costal edges are narrower than the 

 bases and are finely beaded. Intercostal furrows of about the same 

 width as the costae. 



Calices not very definitely arranged, occurring in clusters or in 

 irregular transverse series. Considerable areas are without calices. 

 Each calice is surrounded by from 6 to 9 prominent septo-costae, 

 as tall as 2 mm., and 1 mm. thick. Between these on the upper 

 (distal) side often there are smaller ones. New calices may originate 

 by budding from the costate area. Diameter of fully developed 

 calices, about 4 mm. The septo-costae in the noncaliculate areas 

 are coarse, prominent, and equal. Number to the centimeter, 10: 

 height as much as 1 mm. ; thickness of base, as much as 0.7 mm. 

 Edges rather acute and beaded. Intercostal furrows usually nar- 

 rower than the costae. Synapticulae present. 



