1863.] DT7NCAN WEST INDIAN CORALS. 427 



a small circular base, conical below, cylindrical above, with a slight 

 enlargement below the calicular margin : no trace of adherence. 

 Costse distinct, very slightly prominent, blunt ; those of the primary 

 and secondary septa are visible to the base, being most prominent at 

 the calicular margin; at the enlargement they are ragged. The 

 tertiary costse resemble the primary and secondary when there are 

 higher orders of septa ; but when there are not, they only extend a 

 little way from the calice, and are small. The fourth and fifth orders 

 of septa are continuous, with short and very small costae. Wall very 

 faintly granular. No epitheca nor exotheca. Calice circular ; its mar- 

 gins and axes are on even planes ; fossa shallow. Columella large, 

 essential, presenting at the free surface numerous small, free, cylin- 

 drical, papillary elevations, the largest being external, Pali very in- 

 distinct, and feebly developed. Septa crowded, in six systems of four 

 cycles ; incomplete. Septa of the fourth and fifth orders wanting 

 in four half-systems; primary and secondary well developed and 

 equal, thin, and not larger at any part than at another ; straight, but 

 slightly exsert and arched. Laminae marked with a few distinct and 

 prominent papillae. The tertiary septa are larger when the higher 

 orders of septa are present, and resemble the secondary ; but when 

 these are absent, they are like the fourth and fifth orders — linear, 

 rarely granular, and often bending laterally. 

 From the Mvaje shale. Coll. Geol. Soc. 



Dimensions. — Height of the largest specimens equal to the breadth; 

 of the smaller greater than the breadth — from ^ to J inch. It is 

 evident that, were the septal cycles complete, the breadth would in- 

 crease still more ; and also that the growth of the coral is at first 

 in excess longitudinally, then transversely. The specimens are very 

 hard and calcareous. 



One specimen with the larger costae more decidedly dentate supe- 

 riorly must be considered to constitute a variety of this species. 

 From the Nivaje shale. Coll. Geol. Soc. 



The twelve specimens of this species which I examined presented 

 the above-mentioned structural details, except one, which was con- 

 sidered a variety. The breadth of the corals in their young stage, 

 their large papillose columella, and their small pali lead to their 

 comparison with Bracliycyathus Orbignyanus, Edwards & Haime; 

 nevertheless there is only a remote affinity. Their small pali and 

 undecided transverse development must be considered, with the de- 

 fective fourth cycle, as indicative of immaturity. The new forms 

 do not fall within any other generic definition, and the varying deve- 

 lopment of the pali in the Ccenocyathi must be remembered before a 

 great value is placed on this peculiarity. The genus Bracliycyathus 

 has hitherto included only one species, which is closely allied to the 

 shorter Cyathina;. Duchassaing and Michelotti have formed the genus 

 Paterocyaihus to admit a form which differs from Bracliycyathus in 

 being turbinate, and having the upper part of the wall strongly 

 striated, the pali being in a simple crown. The specimen described* 

 by them came from the Upper Tertiary beds of Guadaloupe. If the 



* Mem. Acad. Turin, 2nd series, 1861, vol. xix. p. 336. pi. 5. fig. 11. 



2g2 



