STRATIGRAPHICAL DISTRIBUTION. 



Viscount d'Archiac has accordingly presented us with the following Table 



107 



Distribution of the Class 



according to 



Viscount d'Archiac. 



a 

 c 



cj 

 O 

 cj 



o 



CJ 



g 



t>5 



a> 



'3 

 cj 

 Oh 



CJ 

 O 



5 

 £ 

 1 



CJ 



R 



S 



J3 



CJ 



o. 

 c 



& 



"ci IT 

 J= CS 



°<§> 



a 

 a 



"3 



G 



s 



o 

 -J 



-a 



E 



in 



a 

 cj 



CJ 

 in 



O 



CJ 



5" 



"3 



o 



•n 

 c 



W 



C 



a) 



03 



6 



aj 

 o 



c3 

 IS 



c 

 o 

 >■ 

 <o 

 Q 



o 

 ^a 

 c 

 ea 

 in 



o> 

 a? 



O 



c 



c 

 *? 



J- . 



Cj -^ 



A. s 



"3 "g 

 -2 ^ 



cj 



o ~> 



S o 



s •* 



o 

 cj 



a> 



'o 

 a) 



in 



5 

 c 



l« 



i« 



s s 



s - 



So 



CJ 

 CJ 



a, 



-3 



c 

 a 



5 g 



O 4j 



P 



5 2 

 So 



03 



in 



is 



£ 



s 



CJ 

 Cj 

 s~ 

 CD 



s- ^* 



cj ^ 



§. S 



A, e 



l| 



o o 



c T3 



§^ 



c a 



s 



o 

 cj 



cj 

 *o 



03 

 Oh 



zn 



<9J 



c 

 a 



"is 

 a 



cj g 



3% 

 3 § 



s 



o 



CJ 



</> 



CJ 



'a 



CJ 



a. 

 en 



C3 ^ 



CJ CJ 



»s 



CJ CJ 



° 3 



a -a 

 o c 

 c a 



B'SS 



c s 

 cj e 



cj cj 

 'cj J3 



£3 



s 



C CJ 



c- a 

 s. | 



a. s; 



^^ 



S «5 



5 



1 o 



s-g 



_o 

 "o 

 <u 



Oh 



(/a 



Brachiopoda . . 



5 



52 



18 



11 j 10 



5 



22 



5 



5 



— 



2 



— 



1 



2 



3 



And I now place into corresponding Columns the results arrived at during the publication of the 



present Monograph. 



According to Mr. Davidson. 

 Brachiopoda . . 



2 S 



CJ w JD 

 O 3 



13 



about 

 49 



14 

 or 

 15 



15 



28 

 or 

 30 



7 

 or 



8 



8 



— 



7 



6 



8 



6 



1 2 



2 

 or 

 3 



Although fifty-two species are recorded in the French author's table, and only forty-nine 

 in our own, still in reality the last number greatly exceeds that presented by the Viscount, 

 because, at least twenty-two to twenty-four of his names are synonyms, while my list 

 contains a number of species new to England, and mentioned in no other publication. 

 But I must at the same time hasten to announce, that notwithstanding all the care, 

 researches, and consultations undertaken in the identifications of the species, I have not 

 always arrived at results which can be considered finite, and possibly forty-five good species 

 may comprise all that have been hitherto discovered in British Cretaceous Strata. 



Much additional investigation will likewise be required before the exact stratigraphical 

 repartition of certain forms can be definitely established ; and to arrive at this most im- 

 portant geological desideratum, it will be necessary to settle in a definite manner the 

 comparative age of certain beds above the Gault in the Isle of Wight, at Cambridge, 

 Farringdon, Chardstock, and in a few other localities. 



Thus, according to the generality of British geologists, the Farringdon Sponge Gravel 

 would belong to the age of the Lower Green Sand; by myself, to that of the Upper Green 

 Sand or Tourtia .- 1 and by Mr. Sharpe, more modern than the Chalk, or in other words, to 

 the Upper Maestricht {Cretaceous) beds and Pisolitic Limestone of Laversine (France). 



1 See 'Bull, de la Soc. Geol. de France,' vol. xi, Feb. 1854. I believe this view is likewise sanctioned 

 by Mr. S. P. Woodward. 



