part 4] 



JURASSIC CHRONOLOaX: LIAS. 

 Table IX (contimced). 



277 



Faunal Horizons. 



Areas. 



Deieix. 



Age of 



Ox3'cone 



Avietids. 



See p. 269. 



Mercian. 



Age of 



Catageiietic 



Arietids. 



See p. 271. 



Ltmian. 



Age of 

 Anagenetic 



Arietids. 

 See p. 273. 



f 8. (li/mense) 



I 7. RadstocJcice^'as 



I 6. G-leviceras 



J b. poli/ophylium 



4. oxi/notum 



3. biferum 



2. simpsoni 



;^ 1. Gagaticeras ! ... 



f 7. denotatus | ... 



I Q. stellare I ... 



I 5. planicosta i ... 



-<j 4. sagittarium ... 



I 3. obtnsum ' ... 



I 2. hroolci ' X 



1^ 1. turneri X 



f 8. birchi X 



7. Arnioceras X 



I 6. Agassiceras X 



J o. gmuendense ; X 



I 4. verciagetorix > ... 



I 3. bucJclandi j ... 



I 2. rotator 



1^1. Vermiceras { X 





xl 





X 



X 



... 



X 





X 





X 



... 





X 



X 



X 



X 





X 



X 





X 





X 





X 



X 



X 



X 



? 



? 



■?■ 





X 



^ 



X 



[For the Hettangian sequence, see Appendix by Mr. Tutcher, p. 278.] 



1 Suggested on the evidence of a fauna in the Yeovil & Bridport Sands. 



a See S. S. Buckman & E. Wilson, Q. J. G.S. vol. lii (1896) p. 688, footnote 2. 



3 In Wiirtemberg Quenstedt's Lias e ( = middle and lower parts of Whitbian) 

 seems to be fragmentarj'; but, on tlie other hand, it would appear to possess certain 

 horizons of its own not j'et separated out in other areas. 



■* FrecJiiella subcarinata is a notable and ea'^il}' recognized species; but, perhaps, 

 souiewhat too rare to be quite suitable for this scheme. It is in use for the horizon 

 where Hildoceras-bifrons forms are abundant. To prevent misconception it is 

 advisable to analyse further. F. subcarinata without H. bifrons forms is not yet 

 known to me ; but the latter are found where the former is lacking. 2^. subcarmata 

 occurs in Yorkshire, the Midlands, in Somerset, but not in Dorset nor Gloucester- 

 shire. It occurs in the Rhone Basin, the Austrian Alps, and Italy, but not in 

 Wiirtemberg. Its rarity may account for its absence, say, from Gloucestershire, 

 but can hardly be pleaded for the well-searched Dorset Coast, and certainly not for 

 so well-worked an area as Wiirtemberg. Absence of a special deposit seems to be 

 the explanation required there. 



^ The fauna of horizons 1-3 are illustrated in Reynes, ' Geol. Pal. Aveyron.' 1868 

 Monestier's paper, _;fl»i cit., refers to the same district. 



