GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 429 



protuberances. The width of the frond as given is the true width, 

 for the specimen is not broken on its lateral edges. Common wall 

 solid, naked. Calices are confined to one surface. The outer surface 

 is longitudinally finely costate; 16 costae, alternating in size, were 

 counted within 5 mm. in two areas. The costae are low, triangular 

 in profile, their bases meeting or with an exceedingly fine costal thread 

 between them. These costal threads are not included in the count 

 of costae within 5 mm. as given above. A row of small granulations 

 along each costal edge. 



Calices swallow-nest-like, tend to be arranged in concentric rows 

 and series; lower side protuberant about 3 mm. Distance between 

 calicular series 4 to 7 mm. In the same series adjacent calices con- 

 fluent but with separate centers; isolated calices may form part of 

 the same row. Transverse diameter of isolated calices from 2.5 to 

 4 mm. 



Septa in largest isolated calices 24 in number, 10 of which extend 

 to the columella; as a rule alternately longer and shorter, and alter- 

 nately more and less exsert. Septal margins over the edges of the 

 protuberant side of the calices steeply arched but not pointed. 



Septo-costae with very thin edges, as a rule alternately taller and 

 lower; 16 within a linear distance of 5 mm. The septo-costae from 

 the upper side of a lower calice or calicular series extend as septo- 

 costae to the next higher calice or calicular series and continue as 

 the septa of the higher calice or series. Synapticulae are highly 

 developed. 



Columella a wide, thin, prominent, axial plate. 



Locality and geologic occurrence. — Santo Domingo, station No. 7778, 

 Rio Curabo, zone G, collected by Miss C. J. Maury (type), associated 

 with Placocyatlms variabilis Duncan. 



Cuba, station 3461, gorge of Yumuri River, Matanzas, collected by 

 T. W. Vaughan. 



Type.— No. 324973, U.S.N.M., presented by Miss C. J. Maury. 



Agaricia dominicensis differs from A. anguillensis by the greater 

 tumidity and prominence of the lower lips of the calices or calicular 

 series ; in fact, the lower edge of the calices in A. dominicensis is carried 

 upward so that usually it is as high as or higher than the upper side 

 of the calicular aperture. It also differs from A. anguillensis in its 

 thin, prominent, platelike columella. 



The living Agaricia nobilis Verrill, 1 found in Florida, Turks Island 

 (West Indies), and Porto Rico, is near A. dominicensis. A. nobilis 

 has still a more prominent calicular lip, and more prominent and 

 strongly alternating septa and septo-costae. 



1 Conn. Acad. Arts and Sci. Trans., vol. 11, p. 150, pi. 28, figs. 1, 2, 1902. See also Agaricia elephantotus 

 Vaughan, U. S. Fish Com. Bull, for 1900, vol. 1, p. 310, pi. 17, fig. 1. 



