166 



INFERIOR OOLITE AMMONITES. 



The correlation of the sections previously given with these, and their arrange- 

 ment into beds, will be facilitated by the following table: 



Name of Beds.* 



Haresfield, 

 p. 43. 



Coaley,' 

 p. 45. 



Nibley, 

 p. 46. 



Burton Bradstock, 

 p. 47. 



Opalinum 



Moorei 



Dumortieria^ . . . . 

 Dispansum . . . . 

 Striatulum . . . . 



Nos. 8—15 

 „ 16, 17 

 „ 18,19 4 



> Absent < 



Nos. 3, 4 



„ 5,6 



Not identified 



No. 7 

 „ 8, 9 



Nos. 4, 5 

 ,, 6,7 

 „ 8-11 

 „ 12, 13 

 „ 14, 15 



Nos. 3, 4 



!•■■ 



The Yeovil Sands contain part of the Opalinum-, the Moorei-, and the Bumortieria- 

 beds of the Cotteswold district, so that their deposition did not commence until 

 after the deposition of the Cotteswold Sands had concluded. 



The Midford Sands contain, at any rate in the lower part, Gramm.fallaciosum, 

 indicating the presence of the Dispansum-heds ; while at the base lies a bed with 

 Gramm. striakdum, cemented on to a very thin layer of the Commune-zone, which 

 in turn is cemented on to the Falcifenim-zone. The matrix is different in each 

 case, but more noticeably between the two lower. 



At Little Sodbury the sands are only about thirty-five to forty feet thick. 

 What the lower part contains is unknown, but the upper part contains Ammonites 

 signifying the horizon of the Dispansum- and Striatulum-heds. Consequently the 

 deposit of yellow micaceous sands began and finished earlier in the north, and as 



1 The word "beds" is used as of less value than "zones." The two higher beds I have con- 

 sidered as the Opalinum-zone, the three lower as the Jurense-zone ; but a really sharp line cannot be 

 drawn between them anywhere. It must be understood that I do not pretend that even the species 

 which gives its name to a bed is confined to that horizon, but only that I have found it dominant 

 therein. 



2 In section vi, p. 45, occurs a printer's error : Striatulum-suhzone should not be opposite C", 

 but opposite bed 7, which should be marked C. 



3 Bed 19 at Haresfield (p. 44) belongs to the Dumortieria-heds. The true Striatulum-heds are 

 apparently wanting there. 



* Dmnortieria-heds I had not distinctly recognised when Part II was written because I 

 had not visited the exposures where the strata are typically developed. The Ammonites of all 

 the Cotteswold developments o£ the Dumortieria-heds are extremely poorly preserved. Unfortunately, 

 the strata of the Opalinum- and Jurense-zones, especially in the Cotteswolds, do not yield Ammonites 

 in good condition, and hence much of our work among the species of the genus Grammoceras is 

 rendered very difficult. But the genus Dumortieria suffers even more from the poor preservation of 

 its specimens, because the specimens in the Dumortieria-hedm are in much the worst condition. 



