324 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Juiie 15, 



nected with the works some interesting facts were disclosed, tending 

 to the inference that this portion of the stratum was deposited under 

 very quiescent conditions. The lias was finely laminated, and inter- 

 stratified with it were thin, tabular, calcareo-siliceous layers or sep- 

 taria, containing abundantly the Posidonia Bronnii (now first recorded 

 as British), and perfectly regular zones of two or three species of 

 Ammonites in every stage of growth, from the most minute (about 

 the size of a pin's head) to their full-grown or usual size — indicating, 

 as it were, a colony of these creatures which must have lived and died 

 on the spot. Aptychi were associated with many of the Ammonites, 

 and with them were examples of Orbicula rejlexa. Sow. 



Remains of insects and of fish were obtained from this portion of 

 the deposit ; a fact in accordance with their mode of occurrence in a 

 similar position, as regards the upper lias of Dumbleton, Alderton, 

 and Ilminster*. 



Although the inferior ferruginous oolite is not visible in the next 

 cutting to be described, its range, position, and thickness are fully in- 

 dicated, in ascending from the river to the level of the railway, by 

 the surface of the ground and the occurrence of springs at the line of 

 its junction with the lias : the thickness may be estimated at about 

 30 feet, the upper part occurring a little below the level of the line. 



The Little Ponton Cutting next follows, and in which, as briefly 

 noticed in Part I. p. 318, the oolite rocks are much disturbed and 

 fissured, the dislocated beds lying at great angles, in various directions 

 and very irregular ; besides which, a small fault is visible in the great 

 sand-pipe in the cutting. At certain parts, however, the strata 

 are tolerably parallel. The greatest depth of the cutting is about 

 50 feet, and consists of the following descending series : — 



feet. 



Rubbly oolite, composed of rag and very comminuted shelly 

 beds 



Compact shelly beds, thick-bedded, some pisolitic 15 



A thin band of slaty clay — 2 to 3 inches. 



Compact marly and shelly rock, with Lucina, Pinna, Ostrea, 

 Avicula, Trichites, Corals 5 



Marly oolitic rock, containing Gervillia acuta 5^ 



Compact marly rock, with few oolitic grains 1 



Thin vein of clay — 2 or 3 inches. 



Coarse-grained oolitic rock , 6 



Stratified grey sandy clay \\ 



Marly oolite, full of small Pecteus 0^ 



Compact marly and sandy rock, with Gervillia acuta, Tri- 

 gonia Phillipsi 3^ 



Ferruginous sandy oolite, with shells in fragments 1 



* From the first two localities, Mr. W. R. Binfield has kindly sent me, for com- 

 parison, specimens containing insects and the same species of Ammonites. See 

 also Murchison's Geology of Cheltenham, 2nd edit, by Buckman and Strickland, 

 p. 35; and Brodie's Fossil Insects, p. 55. The insect and fish remains of Jlminster 

 are noticed in an interesting paper on the fossils of the Upper and Middle Lias 

 of that locahty, communicated by Mr. C. Moore to the Somerset Archseological 

 and Natural History Society, 1853. 



