PLATE XL. 



CARBONIFEROUS SPECIES. 



Fig. 



1. Productus giganteus, Martin. Internal cast of the ventral valve, from the Car- 



boniferous limestone of Lowick, Northum- 

 berland, and from the same specimen which 

 was represented under another aspect 

 in Professor King's ' Permian Monograph.' 

 The letters are the same which have 

 been made use of in the interior, PL 

 XXXVII, fig. 1. 



2. „ „ var. P. EtMburgennis, Phillips. Prom a specimen in the 



Carboniferous limestone of Yorkshire. 



3. ,, ,, A decorticated specimen or cast, from the Carboniferous 



limestone of Thornton, Wensleydale, showing a peculiar 

 interruption and bifurcation of ribs. 



4 to S. ,, ,, var. ? P. kemispfiaricw, Sow. Prom the Carboniferous 



limestone of Craven, in Yorkshire, where the shell occurs 

 by millions. 



9. „ „ Prom one of the original and typical specimens of P. Jtcmi- 



sp/iaricus, Sow., from the mountain limestone of Mynidd 

 Craig, near Kidwelly, in Carmarthenshire. 



