74 PA.L/EOZOIC CORALS AND FORAMINIFERA. 



shaped rims of growth^ concave above and produced by the 

 successive growths from the centre leaving the prominent 

 edges of the previous cells ; weathered surface finely striated 

 by the edges of the vertical lamellse, of which there are about 

 twelve in a quarter of an inch : the horizontal oval section shows 

 the centre to be excentric, close to one of the broad sides, and 

 formed by the twisting of the radiating lamellae about an ima- 

 ginary axis ; radiating lamellae very thin, of equal thickness, 

 about 115 to 130 at the margin, some stopping and some 

 uniting as they approach the centre, about which they are 

 twisted in parcels ; all the lamellse connected throughout, at 

 regular intervals, by minute transverse vesicular plates : in- 

 ternal structure exposed by horizontal and vertical sections, 

 uniformly and minutely cellular. 



The great number and closeness of the lamellse distinguish 

 this species from those published forms allied to it. 



Rare in the lower carboniferous limestones of Arnside, Kendal, 

 and Lisardrea, Boyle, co. Roscommon, Ireland. 



[Col, University of Cambridge.) 



Cyathaxonia costata (M*^Coy). 



Sp. Char. Elongate-conic, generally about one inch long and 

 half an inch in diameter at the cup, which is circular and 

 horizontal ; surface irregularly wrinkled transversely, and 

 marked longitudinally with remarkably thick, strong, sharply- 

 defined striae, about seven in one-fourth of an inch ; central 

 solid axis very thick (often one line in diameter), and from it 

 twenty-six thick, wedge-like, vertical lamellae radiate to the 

 walls ; transverse vesicular plates connecting the lamellae ex- 

 ceedingly delicate ; in the sections the vertical lamellae are seen 

 to dichotomise upwards, and the large curved plates of the 

 loose vesicular structure incline upwards and inwards towards 

 the axis. 



This is more slender in form than the C. mitratum (Schlot. sp.) 

 or C. cornu-copia (Mich.), and from which and all the other tur- 

 binated corals of the palaeozoic rocks it is distinguished externally 

 by the strong, distinct, distant longitudinal ridges ; the internal 

 characters approximate it only to the Cyathaxonia cornu (Mich.), 

 from which it is distinguished by its simple, few and thick la- 

 mellae and thick axis, as well as more turbinate form. 



Rare in the carboniferous limestone of Derbyshire. 



[Col. University of Cambridge.) 



