678 MESSRS. S. S. BIJCKMAN AND E. WILSON [Nov. 1 896, 



Section I. (continued). 



ft. ins. ft. ins. 



Striatuli. 28. Greenish-grey, earthy limestone, 

 coarsely ironshot. Gr. striatulum. 

 Pectens, beleinnites 2 



Bifrontis. 29. Blue, argillaceous limestone, irre- 

 gularly speckled with large iron 

 grains. Hildoceras bifrons, be- 

 lemnites. RhynchoneUa sp 2 



Falciferi. 30. Pinkish argillaceous limestone, 



very few iron grains. Harpo- 

 ceras falciferum, Dactylioceras 



Charmouthian " ° 2 



Age. 



31. Greenish-blue clay visible 7 



Beginning at the base, the first point to notice is the absence of 

 the marlstone — a fact also further confirmed for the western part 

 of the hill by excavations at Elwell Spring giving the same result. 

 As will be seen in later sections, the marlstone is found in places 

 interposed between beds 30, 31. 



Next, the thin deposits (Nos. 27-30), yielding the same species of 

 ammonites as the base of the ' Cephalopod-bed ' of the Cotteswold 

 range plus i Upper Lias,' are important ; and then the thick mass 

 of clay (No. 2Q) proved at the other end of the hill to have been 

 deposited during the Dumortierias hemera, contemporaneously with 

 the middle part of the Cotteswold Cephalopod-bed. All these 

 deposits show a thickness of about 50 feet, which would have been 

 formerly called ' Midford Sands and Upper Lias ' — a marked differ- 

 ence from the results given by Etheridge and Stoddart (see pp. 671, 

 673). 



The evidence concerning the deposits made during the bradford- 

 ensis and Murchisonce hemerse is not very satisfactory here ; and it 

 could hardly be so without excavations made on a much more 

 costly scale than we were able to undertake. Zeilleria anglica, 1 

 however (see Nos. 19 & 22), marks a very definite horizon in 

 Dorset 2 ; it lived more or less contemporaneously with Ludivigia 

 Murchisonce, and perhaps died out just before Lioceras bradf or dense \ 

 but on this point further evidence would be desirable. 



Above the horizon of Zeilleria anglica, the next noticeable datum- 

 line is that of Bed 8 with JSonninia aff. ovalis, Quenstedt. Between 

 these two horizons are certain beds with species of Hyperlioceras in 

 the upper part and species of the concavum-ty^e lower down. 3 



Lastly, it is to be noted that the planed-off top, indicating denu- 

 dation, appears on a bed which we assign by its ammonites to the 

 deposit that we shall hereafter call the Lower White Ironshot, 

 consequently there is a distinct non-sequence between Beds 4 and 3, 

 which is partly filled by some strata met with in sections to be 

 described presently. 



1 See note, p. 702. 



2 See 'The Bajocian of the Sherborne District,' Quart. Journ. Geol. Soc, 

 vol. xlix. (1893) p. 489. 



3 The peripheral areas of Hyperlioceras and of the concavum-type of ammonite 

 leave distinct impressions, the former bitabulate J\ , the latter fastigate y\, . 



