HILL: GEOLOGY OF JAMAICA. 235 



STYLOCCENIA, Edwards and Haimb. 

 Stylocoenia duerdeni, sp. nov. 



Plate XXXVII. Figs. 1-4. 



1865. Sti/locoenia emarciata, Duncan (non Lamarck), Quart. Jour. Geol. Soc. Lon- 



don, Vol. XXI. pp. 7, 8, 13. 

 1868. Stij/ocoenia emarciata, Duncan, Quart. Jour. Geol. Soc. London, Vol. XXIV. 



p. 23. 



Form of corallum, a convex mass ; type specimen, 28 mm. in diameter on 

 the base and 24 mm. high. The specimen is broken off from a larger piece, as 

 Fig. 2, Plate XXXVII. shows ; therefore the above measurements do not repre- 

 sent the original size of the corallum. Calices shallow, hexagonal, subequal 

 in size, 1.5 mm. to 2 mm. in diameter, close together, separated by a simple 

 wall which is from a quarter to a half millimeter thick; often there are thick- 

 enings at the corners of the calices, and remnants of what appear to have 

 been pillars. Septa sixteen, eight large, which fuse to the columella, and 

 eight small shorter ones. Dissepiments present, apparently numerous, very 

 thin, in places may be close together, .5 mm. apart. The columella is 

 styliform. 



Locality. District of St. Marj'-, Parish of St. Mary, Point Haldane (Institute 

 of Jamaica) ; Port Maria (Geological Society of London). 



Type. Collection of Institute of Jamaica. 



The specimen that has come under my observation does not permit a more 

 detailed description. The description and figures seem sufficient to make the 

 species recognizable. This is undoubtedly the same as Duncan's Stylocoenia 

 emarciata^ as a comparison of the above description with the notes already 

 given on his original specimen will show. The Stylocoenia duerdeni seems to 

 me distinct from Stylocoenia emarciata, both from the descriptions of the latter 

 and after a comparison with specimens of the latter in the U. S. National 

 Museum. The calices of emarciata are much larger, the maximum diameter 

 being 3 mm. The usual diamete# is 2.5 mm. or a little more, while in 

 duerdeni the usual diameter is between 1.5 and 2 mm., with 2 mm. as a maxi- 

 mum. This makes a difference in size of almost a millimeter. Although the 

 specimen of duerdeni is worn, in places the surface does not appear to have 

 lost much from attrition, so one can determine the depth of the calices. They 

 are much shallower than in emarciata. 



MULTICOLUMNASTR^A. gen. nov. 



This genus is closely related to both Orbicella, Dana, and Columnastrcea, 

 d'Orbigny. In the description of the only known species of the genus much 

 detail is given, so here only the more general characters will be pointed out. 



