194 Carter — Fossil Sponge- Spicules from Ben Bulben. 



composed of them), rendered still more fragmentary by partial removal so as 

 to leave nothing but their moulds, as before stated, are those which at last 

 come out entire, so far as they go, in the washing of the " clay." 



It is remarkable, too, that by far the most plentiful among Mr. Thomson's 

 collection of spicules from the clay near Glasgow is that of Holasterella con/erta, 

 as it is that of H. Wrightii at Ben Bulben; the "sausage-shaped" spicule 

 (fig. 14) is also analogous to that of the supposed Renierid sponge (' Annals,' 

 1879, vol. iii. pi. xxi. fig. 11), and about the same in frequency. In Mr. 

 Thomson's collection were also fragments of Lithistid spicules ; and last 

 summer he sent me a section of an entire sponge in Carboniferous Limestone, all 

 calcified, with weathered-out spicules on the surface, but none of it sufficiently 

 defined for useful delineation. The collection also contained some zone-spiculeB 

 of the Pachytragida ; so that, altogether, the Spongida appear to have been as 

 plentiful and as varied in the Carboniferous age as at any other time. 



It would be worth while, when the opportunity offers, for some one to look 

 over the weathered surface of the strata in the mountain of Ben Bulben, where 

 fragments, if not entire specimens, of sponges from which the spicules come 

 might be found, after the manner that they have been discovered in the Car- 

 boniferous system in the south-west of Scotland. 



11 FEB # 





