FOSSIL COKALS FROM WEST INDIES WELLS 



79 



The corallum is simple, arising from a small pedicellate base, 

 rapidly expanding, the calice flaring out unequally with an undulate 

 margin. The outer surface is covered to the base by low, acute 

 costae, which regularly alternate in size, marked by single rows of 

 granulations. The wall between them is imperforate and solid, its 

 upper margin where it meets the reflexed calice. On one side of the 

 corallum is attached a young compressed individual, which has been 

 budded off. The calice is convex near the outer margin, but becomes 

 deep and concave centrally, with a very small, deep fossette. The 

 septa are very numerous, thin, crowded, irregularly arranged in six 

 complete cycles and part of the seventh. They are solid, laterally 

 granulated, lightly beaded on the upper edges, unequal in length 

 and thickness. About 18 of the thickest and longest septa reach to 

 the center of the fossette and join the columella. The columella is 

 very small, deep in the fossette, with a papillose upper surface. 



Measurements. — As follows : 



Plesiotype.—U.^.'^M. no. 74491. 



Ocourrence. — Specimen 4 comes from a locality near Catadupa ; 

 specimen 5 is from the equivalent of the Providence shales in the 

 Cambridge-Catadupa railway cut (Trechmann collection). 



Remarks. — The specimen just described is illustrated on plate 2, 

 figures 9, 10. 



A sixth specimen, referred with some doubt to this species, comes 

 from the rudistid limestone in the Logie Green section. It differs 

 from the other forms by the presence of an elongate columellar 

 fossette, but in all other respects is like them. The corallum has 

 been badly worn and measures 31 mm high and 37 by 63 mm in 

 calicular diameters. 



Trochosmilia Mill Vaughan may be a synonym of this species, 

 although Vaughan points out that the sides of the costae are perpen- 

 dicular and that the columella is absent, whereas in Trochoseris 

 catadupensis the costae are acute or rounded. These are the only 

 observable differences between the two forms. The columella in T. 

 catadupensis is usually very small and deep in the calice and is 

 rarely visible even in the larger specimens. 



73594—34 2 



