84 



described by the Eev, J. E. Tenison- Woods, as belonging to 

 the limestone beds of Mount Ganibier, that the description 

 of the latter would almost suffice for the Turritella Group of 

 Table Cape, e.g., in page 75, Geo. So. Austral., the following 

 description of the Mount Gambler beds is given — " It is here 

 seen that in addition to a distinct line of stratification, dividing 

 the rock into layers about fourteen feet thick, there are regular 

 zones where particular fossils are associated. Thus, at the 

 first bed (fourteen feet) little is seen but Bryozoa and 

 Terebratulae ; in ten feet next, less of the moss corals, and 

 mere Pectens ; the next is almost exclusively composed of a 

 Pecten common to this formation with imbricated striae called 

 Pecten cearctatus, and a cellopore coral subsequently to be 

 described ((7. gamhierensis). This state of things is nearly 

 continued to the bottom, where Echini and Eeteporse combine 

 with the general mass." Had the learned author added that 

 the small shell Turi^itella ivarhurtonii was found in great 

 abundance throughout the mass I should have supposed 

 that he was giving an exact description of the Turritella 

 Group at Table Cape. 



THE CEASSATELLA BED. 



We come next to the lowest division of the marine deposit. 

 Eor itself as a rock it hardly deserves to be considered as 

 separate from the Turritella Group, which rests immediately 

 upon it, were it not for the fact that it appears to have been 

 accumulated under different circumstances. The nature and 

 relative abundance of the organisms contained in it also give 

 a character which though most probably brought about by 

 local circumstances is yet most peculiar and sufficiently dis- 

 tinctive. In making a distinction, therefore, between the 

 Turritella Group (b.) and the Crassatella Bed (c), it is not to 

 be understood that the forms of the lower are nowhere to be 

 found in the higher, and vice versa. All that is meant by the 

 distinction is that the characteristic shells of the lower bed or 

 division suddenly diminish in quantity as we enter the higher 

 group and as we ascend even these gradually disappear. 



We also observe that certain forms, especially Corallines 

 and Terebratulae, abundantly appear in the upper beds in 

 bands, which were rarely seen or altogether absent from the 

 lower. 



The Crassatella bed is extremely variable in thickness, for in 

 some places it attains a thickness of three and four feet, while 

 at other places it is reduced to a mere band of 3 and 4 inches 

 thick. Everywhere throughout, however, it preserves a 

 uniform character. 



I have named it in this paper the Crassatella Bed, because 



