62 



J. BUCKMAH" ON" AMMONITES FROM THE 



Fig. 3. — Termination of Ammonites Braikenridgii, Sow. 

 a b 



a. From the side. b. From the front. 



Our Cephalopoda-bed is on the same horizon as the bed from 

 which the Ammonite just quoted was obtained, Dundry being the 

 extreme western extension of the Oolitic system which prevails in 

 Dorset and Somerset, which latter has so much resemblance, as evi- 

 denced by fossils, to the Inferior Oolite of France. 



This fossil is usually found most abundantly at Clatcombe, near 

 Sherborne, where examples with the curious terminations are not 

 uncommon ; and it illustrates one of those cases in which a different 

 species of the genus occurs at one quarry from that which prevails 

 at another. It is occasionally found at Bradford Abbas, where the 

 prevailing Ammonites are A. concavus and A. Sowerbyi. 



The terminations in this species are among the most perfect, as 

 well as the most frequently met with. The spathulate projection 

 varies greatly both as to length and breadth. 



5. A. lixgtjiferus, D'Orb. pi. 136. figs. 1 & 2. 



Has a neat form and a less broad spathulate termination than the 

 preceding, though closing up the aperture of the shell more by 

 reason of its beading inwards. It is thinner in the whorls ; and 

 the ribs are in threes at the back of the shell, uniting into one, with 

 a tubercle in front. Sometimes there is an intermediate rib between 

 a pair, with three-ribbed vaultings. 



This shell is by no means so frequent as A. Braikenridgii, but 

 occurs in the same places, intermixed with it. 



6. A. Satjzei, D'Orb. pi. 139. figs. 1-3. 



The termination of this shell is much like the former ; but its 

 ribs are much larger, and the shell broader. It is also inclined to be 

 unsymmetrical, and has but few whorls. 



