S32 Mr. Parkinson on the Strafa, 



larly the case with the small pectens^ the moctr<e^ and the left-turned 

 tvhelk. 



From the excellent state of preservation In which many of these 

 shells have been found, it has been thought that they could hardly 

 be regarded as fossil. Many acknowledged fossil shells however have 

 undergone much less changes than those of this stratum ; the original 

 coloured markings are entirely discharged, and the external surfaces 

 are deeply penetrated with a strong ferruginous stain ; the inner 

 surfaces also are considerably changed, their resplendence being su- 

 perseded, to a considerable depth, by a dead whiteness, the conse- 

 quence of the decomposition of this part of the shell. 



Like the fossils of most other strata this assemblage of shells ma- 

 nifests a peculiar distinctive character. A few shells only, which 

 may be placed among those which are supposed to be lost, or amon^ 

 those which are the inhabitants of distant seas, are here discoverable ; 

 the greater number appearing not to differ specifically, as far as 

 their altered state will allow of determining, from the recent shells 

 of the neighbouring sea. 



Among those, of which no recent analogue is known, appears to 

 be the terebratula, figured in Dale's History and Antiquities of Har- 

 wich, &c. tab. XI. fig. 9. p. 294, and described, Phil. Trans. No. 

 291, p. 1578. Mr. Dale describes this shell as Concha loiiga 

 foss'ills fasciata^ and remarks that he has not observed " either in 

 ** Aldrovandus, Rondeletius, Belonius, Qesner, Johnson, Lister, or 

 " Bonanus, any shell that resembles this our fossil, unless it is one of 

 " those figured by Lachmund, p. 43, No. 6 and 7, the inward part 

 *• resembUng our fossil.*' The shdls figured by Lachmund are un- 

 doubtedly ierebratula^ but they manifest no particular agreement 

 with this fossil. 



This shell appears to be figured by Lister, Eistor, ConchyL tab* 



\ 



