1863.] DUNCAN — WEST INDIAN COKALS. 443 



IV. MONTSERRAT. 



1. Astr^a Antillarum, spec. nov. 



A specimen in the form of a rolled flint, found with silicified Wood, 

 has the corallum large, tall, probably resembling in shape that of 

 the San-Domingan A.eccothecata. Corallites close, unequal in size, but 

 quite distinct ; the transverse section shows them to be circular in 

 outline. Septa in six systems of three cycles. The primary and 

 secondary septa are nearly equal, and reach to the columella ; the 

 tertiary are small and straight ; all are slender, wide apart, and very 

 distinct. Costse tolerably developed, subequal. Walls moderately 

 developed, by no means strong. Columella small, and occupying a 

 small space. Endotheca greatly developed, vesicular, and forming 

 cells between the septa. Exotheca well developed ; large cells broad, 

 others squarer, with shelving dissepiments. Diameter of the coral- 

 lites ^j inch. 



The interspaces are filled with opalescent or porcellanous silica ; 

 sclerenchyma often destroyed. 



Coll, Geol. Soc. 



V. Barbuda, 



1. Cyphastr^ia costata, spec. nov. 



Corallum large, compound, with a large base ; very hard. Coral- 

 lites long, slender, numerous, close, but distinct, except at certain 

 points ; converging from the wide base towards a subplane, slightly 

 gibbous, and irregular surface. Walls very dense, generally in- 

 creasing in density and thickness as they become more remote from 

 the calices ; in some places the walls encroach upon the exothecal 

 space, and the corallites are joined by their walls, a dense structure 

 being formed. Wherever the walls become thicker, it is at the ex- 

 pense of the intercorallite space, and not of the interseptal loculi. 

 Walls thin at the calicular margin. Costae well developed, and 

 forming with the exotheca a very marked structure ; at the calicular 

 margin they project a little upwards, are a little dentate, and 

 slightly prominent along the outer slope of the truncated calicular 

 elevation. They correspond to the septa in number, the primary 

 and secondary costaa being but little larger than the tertiary. They 

 are not crowded, but have a deep fossa between them, are not con- 

 tinuous with those of other calices, but are frequently irregularly 

 projected, and often touch. In longitudinal sections they are crossed 

 by dissepiments regularly during their whole course ; their edge is 

 not simply linear, but each costa presents a series of wedges placed 

 one over the other, the thin end of one wedge resting on the thick 

 end of that below it, the dissepiment intervening. The dissepi- 

 ments project beyond the costal edge, and render it irregular; 

 they are absorbed now and then by the development of the walls. 

 Calices circular, forming low truncated cones ; they are well sepa- 

 rated from each other, and frequently, where four meet, a consider- 

 able space exists. Calicular edge sharp. Fossa very shallow. Colu- 



2h2 



