1867.] JTJDD LIXCOLNSHIEE WOLDS. 



235 



thickness of that portion of the Speeton section which I regard as 

 belonging to the Hunstanton series is about 30 feet ; and we have 

 thus indications of a regular attenuation of these beds southwards, 

 until they finally disappear near Lynn, 



e. Fossils of the Humtanton series in Lincolnshire. — ^While these 

 beds do not afford a great number of species, that of hulividuuls is 

 remarkably large. In the following Kst are the names of all the 

 species I hare observed during my survey of the line of outcrop. It 

 will be seen to be smaller than the corresponding list from Hun- 

 stanton ; but it must be recollected how thoroughly the latter locahty 

 has been explored. With the exception of an Avicida ? an Ostrea, 

 and some specimens too obscure for description, the whole of the 

 fossils in this list have been already recorded from Hunstanton. 



List of Fossils from the Hunstanton Senes of LincolnsMre. 



Spongia paradoxica, Woodw. 

 Apiocrinites rugosus, D' Orb. 

 Cardiaster suborbicalaris, Befr., sp. 

 Serpiila irregularis. 

 Termicularia elongata, Bean, MS. 

 Terebratula biplicata, Sow. 



biplicata, var. Dutempleana, 



Bav. 



semiglobosa, Sow. 



capiLlate, B'Arch. 



Ostrea, sp. 

 Exogyra, sp. 



Inoceramus Coquandianus, B' Orb. 



Crispii, Goldf. 



tenuis, Mant. 



Avicula or Lima (spec. nov. ?). 

 Belemnites minimus, MiU. 



Listeri, Mant. 



attenuatus, Sow. 



ultimus, D" Oi'b. 



Nautilus simplex, Sow. 

 Jaws of Ichthyosaurus campylodon, 

 Carter. 



The locality of this last fossil is somewhat doubtful ; but it was 

 certainly from either the sponge-bed or the lowest portion of the 

 Chalk-marl. 



The presence of perforated shells in this as well as the Louth red 

 chalk would appear to indicate the existence of Carnivorous Gaste- 

 ropods, though no shells of them have been found. The guards of 

 Belemnites minimus are not unfrequently found bored by mistake. 



III. The Beds aeove the Htjk-staxton Limestoke. 



a. General Reimirhs on the Chalh of Lincolnshire. — The time has 

 not yet come for separating the great mass of the chalk-formation 

 in this coimty into zones characterized by their peculiar assem- 

 blages of organic hfe. Indeed such a task has not been accom- 

 plished in the case of the best- explored districts of the chalk, except 

 in a very imperfect manner. On the other hand, every geologist 

 who has examined this formation over any considerable area, must 

 be convinced of the futihty of basing any classification on mere 

 lithological characters, such as the occurrence of layers of flint, or 

 the modifications of the chemical and mineralogical characters of 

 certain beds by the admixture of varying quantities of argillaceous, 

 siliceous, or ferruginous matter with the always predominating cal- 

 careous basis in these rocks. Illustrations of this statement occur 

 plentifully in the district at present under consideration : thus it is 

 certain that the first appearance of layers of flint in ascending the 



VOL. XXTII.— PAET I. S 



