468 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



sides, near the lower edges, the ealices flatten, become larger and 

 more' distant, and are either circular or faintly hexagonal in outline. 

 Diameter from 4.5 to 5 mm.; distance apart, from 0.5 to 2 mm.; 

 the range in the distance apart is the same as on the top, but the 

 ealices are more uniformly separated. The costae are distinct, low, 

 and equal, with numerous intervening synapticulae. 



The number of septa to a calice is the same for both the top and 

 sides, ranging from 26 to a few over 30. They are relatively thin; 

 that is, not so thick as the width of the interseptal loculi, except that 

 they are thickened at the wall and the principals are thickened on 

 their, inner ends, bearing distinct palifornl lobes. The primaries and 

 secondaries are subequal, extend to the columella, and are palifer- 

 ous; tertiaries shorter and thinner within the calice; quaternaries, 

 where present, still smaller. The wall is composed of peripheral 

 synapticulae. 



Columella only slightly developed. 



The preceding description is based on a single specimen — No. 1 of 

 the table. The principal variation shown by the other specimens is 

 in the distance apart and size of the ealices and the number of septa. 

 In specimen No. 3 (see pi. 133, fig. 2) the ealices are usually about 

 0.75 mm. apart; their diameter ranges from 3.5 to 5.7 mm., and, as 

 would be expected, the calicular outlines are polygonal; there are 

 in the larger ealices as many as 40 septa, the fourth cycle, however, 

 in these ealices seems never to be complete, but it is complete in 

 some large ealices of the Antiguan specimens. Palar thickenings 

 can be seen on the larger septa; columella poorly developed. 



Localities and geologic occurrence.- — Island of Antigua at numerous 

 localities in the Antigua formation, collected by T. W. Vaughan. 



Porto Rico, station 3191, in the Pepino formation, 4 miles west of 

 Lares, collected by Robert T. Hill. 



Cuba, station 3467, Canapu River, Manasas trail, collected by 

 Arthur C. Spencer. Station 7511, between Ocujal and Palma, alti- 

 tude about 500 feet a. t., near Guantanamo, Cuba, collected by O. E. 

 Meinzer. Station 7514, 5 miles east of monument H4 of U. S. Naval 

 Reservation, Guantanamo, Cuba, altitude 400 feet a. t., collected by 

 O. E. Meinzer. 



Prof. K. Martin, director of the Geologisch Reichs Museum, Leiden, 

 submitted to me for determination some material from Serro 

 Colorado, Arube, that I thought referable to this species. 1 At the 

 time I studied these specimens I was of the opinion the species 

 belonged to the genus Orhicella. The specimens referred to 0. tenuis 

 in the paper cited are referred in the present paper to Antiguastrea 

 celluldsa (Duncan) Vaughan (see p. 407). 



1 Geolog. Reiehs Mus. Leiden Samml., ser. 2, vol. 2, p. 33. 



