438 MK. S. S. BTJCKMAN ON THE BAJOCIAN [Aug. 1895, 



The last is a differently-shaped fossil, with the ' wing ' much more 

 distinctly separated. 



It would appear from the measurements that there may very 

 reasonably be some doubt as to Avhether Lycett's Gryphcm Buckmani 

 is really the same as the Gryphcea sublobata (Deshayes) ; but there 

 cannot be much doubt that the Grypbite-grit fossils are distinct. 

 Further, the Gryphcea Buckmani is not the true Gryphite-grit form. 

 It has, no doubt, developed iuto the rounded form, because with 

 age there is a tendency to broaden and to make the separation of 

 the wing less definite. The change from Gr. Buckmani into the 

 broad form may have been very gradual, so that most likely both 

 forms will be found occurring together ; but in the lower of the 

 ' intervening beds ' it would probably be found that the long form 

 was the most prevalent, and in the upper that the rounded form 

 has entirely taken its place. To ascertain, however, the vertical range 

 of the different forms would require systematic collecting of these 

 Gryphcece, and the noting of their exact horizons, from different 

 localities. The round form probably requires a name as a distinct 

 mutation. 



4. Gryphite-grit. 



I would call attention to certain remarks in connexion with this 

 deposit at Kimsbury Castle : namely, that the beds are considerably 

 bored and that polyzoa are attached to the Gryphcece both inside 

 and out (p. 403). Now, the presence of the Gryphcece alone points 

 to a very slowly accumulating deposit ; and these other signs bear 

 additional testimony thereto. But that the Gryphite-grit was a 

 slowly-formed deposit is of importance in connexion with its contem- 

 poraneous equivalent in Dorset. That deposit is in many places about 

 one-sixth the thickness. Therefore the Gryphite-grit was deposited 

 6 times as fast as the Dorset bed ; and yet the Gryphite-grit was 

 laid down very slowly. 



At Leckhampton Hill and Charlton Common the thickness of the 

 Gryphite-grit has been stated at 5 feet. This may be regarded as 

 a somewhat approximative measurement, which may appear too 

 much or too little according to whether the rock be well weathered, 

 so that the Gryphcece are prominently shown, or whether it be 

 freshly exposed. But between the sandy beds of the Buckmani- 

 grit containing broad i Terebratulce aff. Buckmaniana,' and the white 

 oolitic stone of the JNotgrove Oolite are about 5 feet of very gryphae- 

 iferous ragstones. The change from the Gryphcea-beda to the 

 INotgrove Oolite is well marked, but from the sandy beds of the 

 Buckmani-grit to the gryphseiferous beds it is not always abrupt — 

 indeed, it is generally somewhat gradual. The broad Terebratula 

 referred to above occurs about 7 feet below the base of the Notgrove 

 Oolite. The sequence from Buckmani-grit to JNotgrove Oolite may be 

 observed at the west end of Charlton Common ; but the Buckmani- 

 grit is not complete. 



