490 BULLETIN 103, UNITED STATES NATIONAL MUSEUM. 



GONIOPORA DECATURENSIS, new species. 



Plate 143, figs. 1, la. 



Corallum lamelliform, the lateral expansion far exceeding its 

 thickness. The specimen selected as the type is a portion of a coral- 

 lum, 90 mm. across and about 23 mm. thick. Another specimen is 

 49 mm. long, 35 mm. wide, and 7.5 mm. thick. The upper surface 

 is plane or undulate. When the corallum is foliaceous, it may be 

 irregularly flexed. 



Calices polygonal, shallow, superficial or only slightly excavated. 

 Usual diameter 2.5 to 3 mm. The wall, when somewhat worn, usually 

 has a membraniform appearance, being almost continuous, inter- 

 rupted in places, but forming a quite distinct boundary between ad- 

 jacent calices. In other instances there may be no well-defined 

 boundary to the calices. Two rows of synapticulae frequently rein- 

 force the wall in the peripheral portion of the interseptal loculi 



Septa of variable thickness on the same specimen, usually mod- 

 erately stout; on the thinner lamellae they are thick. The thickness 

 of the septa seems to be correlated with the thickness of the colony. 

 When the corallum is thick the septa are thin and vice versa. The 

 normal number is 24, although there are in some places a few less, in 

 others a few more. The usual arrangement is six primaries extending 

 directly to the axis, with a triplet group of a secondary and two ter- 

 tiaries between each pair. A directive plane could be observed in 

 some calices, but the septa are too much damaged to permit discov- 

 ering all the details of the arrangement. The margins are dentate, 

 five to seven dentations on each longer septum. The faces with the 

 usual granulations. Synapticulae rather abundant, but not greatly 

 crowded, variable in thickness. 



Columella tangle well developed. 



The texture of the corallum is of variable firmness, depending upon 

 the thickness of the septal trabeculae, the synapticulae, etc., how- 

 ever, it seems never to be especially dense. 



Localities and geologic occurrence.- — -Georgia, station 3381, Blue 

 Springs, 4 miles below Bainbridge; and station 3383, Hale's Landing, 

 7 miles below Bainbridge, Flint River, Decatur County, in the base of 

 the Chattahoochee formation, collected by T. W. Vaughan. 



Cuba, station 7523, Mogote Peak, 250 feet a. t., J mile east of U. S. 

 Naval Reservation, Guantanamo, Cuba, collected by O. E. Meinzer. 

 Type.— No. 325031, U.S.N.M. 



Besides the lot of specimens referred to the species in the fore- 

 going description, three other types or kinds of Goniopora occur on 

 Flint River at Blue Springs and Hale's Landing. It is impossible 

 with the material at hand to decide whether they are distinct species 

 or only varieties or forms of G. decaturensis. However, as it seems 



