FOSSIL CORALS FROM WEST INDIES WELLS 



75 



Family EUSMILIIDAE Verrill 

 Genus DICHOCOENIA Milne Edwards and Haime, 1848 



DICHOCOENIA TRECHMANNI, new species 



Plate 2, Figures 7, 8 



Description. — Coralliim massive, tuberous or bulbous in form. 

 Corallites protuberant above the general surface to a height of 3 

 mm or more, originally cylindrical in form, but usually distorted 

 by fission to an ovate or elliptical shape. Corallites united by costae 

 and a well-developed exotheca; on the surface of the intercorallite 

 areas the costae are distinct, their upper margins covered by single 

 rows of granulations. Calices shallow, varying in diameter from 3 

 mm in the more circular ones to 3 by 4.5 mm in the more elongate 

 and 3 by 7 mm in those undergoing fission. Septa thick, regularly 

 alternate in size, slightly exsert, upper margins entire, lightly gran- 

 ulate laterally. In circular calices there are regularly three complete 

 cycles, the first and second extending to the columella. In the 

 distorted calices portions of the fourth cycle are often developed. 

 Septa much thickened distally to form the corallite wall. Colu- 

 mella spongy, well developed but not prominent, and appearing 

 lamellar in the elliptical calices. Endotheca not abundant. 



Measurements. — As follows : 



Specimen 



1 (type). — . 



2 (paratype) 



3 (paratype) 



Height 



Mm 



Maximum 

 thickness 



Mm 



r^/^e.— U.S.N.M. no. 74480. 



Occurrence. — In the rudistid limestone of the Logie Green section ; 

 and in the limestones near Catadupa, Jamaica (Trechmann collec- 

 tion) . 



Remarks. — This species is particularly interesting because it ex- 

 tends the range of the genus Dichocoenia back into the Mesozoic in 

 the West Indian region. It differs from D. aJahamensis Vaughan 

 (1900b, p. 139) from the Midwayan Eocene by the lack of develop- 

 ment of the exotheca and the resulting close union of the corallites 

 in the latter species. D. tuberosa Duncan (1863, p. 432) from the 

 West Indian Miocene possesses pali and is a larger species. The 

 living West Indian species, D. stokesi Milne Edwards and Haime, 



