1868.] JUDD SPEETON CLAY. 245 



Appendix B. — Notes on the distribution of some of the Speeton-Glay 



Fossils. 



So great is the number of species belonging to the Speeton Clay, a 

 large proportion of them being new, that I propose on the present 

 occasion to notice only such facts with regard to their distribution 

 as may be necessary for establishing and illustrating the conclusions 

 at which I have arrived with regard to the age of the beds. The 

 general examination and description of the fossils will be best under- 

 taken in connexion with those of the Tealby series and the other 

 Neocomian beds of this country, and will be more satisfactorily per- 

 formed after a more extended comparison of them with the fossils 

 of foreign Neocomian strata. 



Nautilus. — All the species of this genus as yet known from Speeton 

 have been obtained from the " Cement-beds." It is interesting to 

 find that we have here the whole of the Lower-Greensand species, 

 viz. N. radiatus, Sow. (N. Neocomiensis, D'Orb.), N. plicatus, Sow. 

 {N. Baquienianus, D'Orb), and N. pseudo-elegans, D'Orb. These 

 species also occur in the Upper Neocomian of Erance. 



Belemnites. — Among the Belemnites of the Speeton Clay there are 

 several well-marked species with limited vertical ranges, which afford 

 considerable assistance in the classification of the beds. 



B. semicanal iculatus (Blainv. ?) — This form is certainly identical 

 with that found in the Lower Greensand ; but I have very strong 

 doubts as to whether it is rightly referred to De Blainville's species. 

 At Speeton it is very abundant in the Upper Neocomian, and scat- 

 tered specimens occur in the Middle Neocomian. 



B.jaculum, Phill. — This well-marked species has received a great 

 number of names — among others, B. minimus, Sow. (pars), B. fusi- 

 . formis, Y. & B. (pars), B. suhfusiformis, E-asp., and B. pistillum, 

 Rom. It is a very variable form, and has been split up by some 

 French authors into a great number of species. At Speeton it is very 

 characteristic of the Middle Neocomian, its metropolis being in the 

 " Ancyloceras-beds." It also ranges downwards into the Speeton- 

 ensis- and Noricus-beds, in the latter of which, however, it is ex- 

 tremely rare. The same species is also abundant in the Tealby series 

 of Lincolnshire, in the Hilsthon, and in the Neocomian of France 

 and Switzerland. 



B. lateralis, Phill. — This species, which is the B. suhquadratus of 

 Romer, occurs in prodigious numbers in the zone oi Ammonites Astie- 

 rianus. In these beds it often reaches a gigantic size, some specimens, 

 being 8 inches long, and 1| inch in diameter. These large specimens 

 are always remarkable for the eccentric mode of their growth, and 

 were among the specimens figured and described by Young and Bird 

 as B. excentralis. The smaller forms of this species occur, though 

 but rarely, in the beds above the zone of A. Astieiianus. 



Ammonites. — Although the fossils of this group are found in con- 

 siderable abundance in the Speeton Clay, their study is nevertheless 

 attended with very considerable difficulties. In a large majority of 

 instances the specimens occur mineralized by pyrites ; and in alrnost 

 all these cases it is only the central portion of the shell which is 



