GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 487 



eral appearance of the corallum is as if composed of superimposed 

 laminae. Calices shallow (?), crowded; diameter, 1.5 mm.; distance 

 apart, quite constantly 1 nnn. Coenenchyma, of superimposed 

 irregularly perforate laminae. Wall, perforate. Septa, perforate, in 

 three complete cycles; 12 septa reach the columnella; the members 

 of the third cycles usually fuse by pairs to the sides of an included 

 septum (the first and second cycles can not be distinguished from 

 each other, and therefore it can not be known whether the septa 

 of the third fuse to the sides of the first or second). Sides granulate. 

 Pali are probably present, but no detail could be made out. Columella 

 very well developed, spongy. 



"Locality. — Salt Mountain, 6 miles south of Jackson, Alabama. 



"(reologic' horizon. — 'Coral limestone,' above Vicksburg beds." 



''I have not been able to decide positively whether this is an Acti- 

 nacis or a Turbinaria. It probably belongs to the latter genus." 



The following is a description of a species of Actinacis, referred to 

 A. alahamiensis, from Flint River, near Bainbridge, Georgia: 



Corallum forming large explanate masses, a foot or more across 

 and 70 to 75 mm. thick. The perpendicular section shows a thinly 

 lamellate structure. 



CaJices small, 1.3 to 1.5 mm. in diameter, usually separated by less 

 than their own diameter of coenenchyma. The coenenchyma is 

 composed of flexuous, perforate, granulated costae, which are fused 

 into a reticulum by abundant S3^iapticulae. The calices are dis- 

 tinctly differentiated from the coenenchyma, but a definite wall is 

 only poorly developed; where it is present, it appears to be due to 

 a zone of peripherally disposed synapticulae. The costae often lead 

 directly across the coenenchyma from one calice to the next, thus 

 joining the septa of adjacent calices. 



Septa slightly less in thickness than the interseptal loculi. The 

 usual number is about 20, the third cycle as a rule is incomplete, 

 arranged with reference to a plane of symmetry. The presence of a 

 directive plane and the grouping of the septa into pairs or groups of 

 threes is characteristic. Pali occur at the junctions of the inner 

 ends of the septa — it seems that the full number is 12. The inter- 

 septal loculi are conspicuously open; if any synapticulae are present, 

 they are rare. 



Columella well developed, composed of septal processes. 



A species of Actinacis, apparently the same as A. alahamiensis, was 

 collected by me in Antigua. It is represented by a small piece 

 61 mm. long, 33 mm. wide, and 25 mm. in maximum thickness. 

 The upper surface is nodose; calices from 1.25 to 1.5 mm. in diameter; 

 coenenchyma composed of a fine trabecular mesh work. This speci- 

 men seems to me to belong to the same species as the specimens from 

 near Bainbridge, Georgia, that I am identifying as A. alahamiensis. 

 37149— 19— BiUl. 103 20 



