50 THE FOSSIL ECHINOIDEA 



Spines of CidaridoB. Plates X. & XI. 



Numerous spines of species of the genera Cidaris, Phyllacanthus (Rhahdocidaris), 

 and Porocidaris are in the collection of Echinoidea from the Ranikot series of Sind. 



Spines of Species op Cidaeis. 



In Plate X. the figures 9 and 10 represent a long tapering spine with a slightly 

 compressed outline, a plain surface for a short distance above the projecting ring above 

 the base of the shaft, and longitudinal rows of small, close, bluntly serrate knobs along 

 the shaft reaching from the plain surface to the tip. 



A larger and more coarsely ornamented spine, with incisions on the ring around 

 the hollow for the tubercle, is drawn at figures 11 & 12. 



A thin, small, and almost plain spine with the milled ring slightly crenulate, on 

 one side, is drawn on figures 13 & 14. 



The locality whence these spines were derived was north by east of Petiani, west 

 of Kotri, in the Eanikot series. Survey-number G y|f . 



The broader, stouter, more fusiform, and more roughly granular and spinulose 

 spines, with slightly triangular and compressed sections, figured on Plate XI. figs. 1-11, 

 are probably those of species of Cidaris. 



Locality/. Hills east of Lynyan, Eanikot series. Survey-number G -f-ff^. 



A Porocidaris spine of great interest is figured on Plate XI. Figure 12. The 

 spine fractured, natural size, and its section. Figure 13. The same, magnified. 



This spine is greatly compressed above the cylindrical base, which has a crenulate 

 ring below the shaft, and also a crenulate ring around the cavity for the tubercle. 



The shaft has a broad central part, from the sides of which numerous stout pro- 

 cesses project obliquely upwards. The front of the flattened shaft has a longitudinally 

 striated ridge ; and the back is slightly convex and striated. The raised striae pass 

 oflF into the lateral processes. 



Locality. Makli Hill scarp, near Tatta, Eanikot series. Survey-number G j-|f . 



Numerous large, much flattened, broad spines, with small crenulate rings, belong 

 to the genus Phyllacanthus {Bhdbdocidaris, Desor). The flat surfaces are ornamented 

 with numerous blunt serrations ; and these are largest at the sides, from which some 

 project considerably. Plate XI. figs. 14-23. 



Locality. Hills east of Lynyan, Ranikot series. Survey-number G fff-. 



