430 PKOCEEDIN'GS OF THE GEOLOGICAL SOCIETY. [May 6, 



tertiary septa of the same size. Laminae slender and granular. In 

 six systems of five cycles. Some septa appear to be united by tbeir 

 inner extremities. Costae subequal, although the septa are alter- 

 nately large and small. Height 1 inch. 



Prom the Nivaje shale. 



In shape the corallum resembles that of Michelin's Turbinolia 

 Japhetii ; but Flabellum clubium has not the dense septa of that 

 species, and is furnished with an epitheca. Flabellum Galapagense 

 and Flabellum crassum have alliances with it, especially the former. 

 Although, from the state of its fossilization, the anatomy of the ap- 

 pendices cannot be made out, still it is clear that there was never 

 any large mark of erosion. The specimen is shorter in relation to 

 the length of the long axis of the calice than is the case in F. Gala- 

 pagense, and the laminar granules are smaller ; moreover the ends of 

 the septa are not very thick. 



6. Flabellum, sp. 



Several casts and portions of a large Flabellum are found in the 

 blue shale of San Domingo, but the specimens are all too incomplete 

 for specific determination. 



7. Thysantjs* coebicula, gen. et spec. nov. PI. XY. figs. 3 a, 3 b. 



Corallum simple, in the shape of an elliptical dish with a rounded 

 and ovoid base, fringed with granular ribs ; apparently it was once 

 attached, but became free by the rupture of a lateral pedicel, the 

 erosion resulting from the separation remaining at one extremity. 

 The base is smooth, and has a central groove. The height is greatest 

 at the end marked by the erosion ; and the base, as it recedes, ap- 

 proaches more or less the calicular margin. Epitheca imperfect, — 

 perfect in the lower half, wanting in a circular groove above it, and 

 again present for a small space above the groove on the portion of 

 the wall remote from the erosion, — smooth, not echinulate or gra- 

 nular, raised into slight ridges which are continuous with the costae. 

 The ridges radiate more or less from the eroded end, and the general 

 growth of the coral appears to start from this point, although the 

 elliptical form is perfect. Groove shallow. Erosion circular, rather 

 deep, ragged at the edges ; it is situated above the epitheca, which 

 bounds its lower half, and is deeply grooved for a short space by it. 

 "Wall hidden by the epitheca and costae ; its general outline is more 

 convex near the erosion than elsewhere. Costae very distinct, exist- 

 ing as ridges when beneath the epitheca, and as prominent granu- 

 lated laminae in the rest of their course. The ridges pass in curves 

 from the part of the base nearest to the eroded end. The costae are 

 alternately large and small, those corresponding to the rudimentary 

 septa of the fifth cycle being very slight ; but the costae of the other 

 cycles are very equal. The granulations are very marked, and are 

 very characteristic ; at regular intervals they swell out the costae, 

 a granule being developed on each side of the laminae and on the 

 free surface. These three irregular growths add to the swellings, 

 * Qvaavos, a tassel. See also Thysani from Jamaica, p. 439. 



