GATTLT AND ETFER CHALK NEAR FOLKESTONE. 441 



Cidaris Bowerbankii. 

 Salenia granulosa. 

 Cardiaster pygingeus. 

 Echinoconus subrotundus (first ap- 

 pearance). 



Discoidea minima? 

 Rhynchonella Cuvieri. 

 Inoceramus labiatus (first appearance). 

 Ammonites (two specimens). 



The Salenia and Cardiaster pygmceus are rare ; but as the latter 

 is very constant, I propose to call this the zone of Cardiaster pyg- 

 mceus. 



Bed IX. (Lower Chalk). 



This bed is measured from the top of the " grit bed " No. VIII. 

 to the first line of flints, the Upper Chalk. It has a thickness of 

 118 feet at Lydden Spout. Its texture is soft; and it is rather a 

 yellowish-white chalk, not quite so pure a white as the Upper 

 Chalk. It is full of fragments of Inoceramus labiatus. This bed in 

 the lower 75 feet is equal to Dr. Barrois's zone of Inoceramus labi- 

 atus, and in the upper 75 feet to the Terebratulina-gracilis zone, in- 

 cluding the previous bed in the zone. 



The following are some of the fossils usually met with in this ho- 

 rizon. 



Ventriculites. 



Bracbiolites quadrangularis. 

 Discoidea minima ? 

 Goniaster mosaicus. 

 Echinoconus globulus. 



subrotundus. 



Cyphosorna simplex. 



Terebratulina gracilis (very common). 



Terebratula semiglobosa. 

 Inoceramus labiatus. 



Curieri. 



Pecten, sp. 

 Beryx. 

 Macropoma. 

 Ptvchodus decurrens. 



This zone is to be considered the horizon of Echinoconus subrotun- 

 dus and Terebratulina gracilis. 



It is somewhat remarkable that most of these zones are the habi- 

 tats of peculiar and restricted forms of Echinodermata ; but two out 

 of the nine beds have no distinctive Urchin. 



They may be enumerated as follows : — 



IX. Echinoconus subrotundus. 

 VIII. Cardiaster pygmoeus. 

 VII. 

 VI. Holaster subglobosus. 

 V. Hemiaster Morrisii and Pcltastes clathratus. 

 IV. 



III. Discoidea subuculum. 

 II. Holaster lavis. 

 I. Pseudodiadema, sp. 



The exception is No. VII., which is the Belemnites-plenus 

 zone, and bed IV., where Radiolites Mortoni is only found. Bed I. 

 certainly contains a Pseudodiadema ; but that is probably P. variolate^ 

 common to several of the higher beds. 



Before concluding this paper, I take the opportunity of thanking 

 Mr. Jukes-Browne, Dr. Earrois, and others who have rendered me 

 assistance. 



2g2 



