PLATE XXXVII. 



CARBONIFEROUS SPECIES. 



Fig. 



1. Product us giganteus, Martin. Interior of the ventral valve, from which a por- 



tion of the beak has been removed, so as to 

 exhibit the umbonal cavity, a and c, Adduc- 

 tor or occlusor ; r, cardinal or divaricator ,• 

 muscular impressions ; l, cavity occupied by 

 the spiral arms. 



2. ,, „ Interior of the dorsal valve, j, Cardinal process; a, adductor 



or occlusor, muscular impressions ; w, projections to 

 which Mr. S. P. Woodward supposes the oral arms 

 to have been attached (?) ; x, reniform impressions ; 

 z, eminences corresponding to the hollows (l) in the 

 ventral valve. 

 :j. „ ,, Hinge-line and cardinal process of dorsal valve. 



These drawings are taken from valves belonging to 

 the same individual, which was obtained from the 

 Carboniferous limestone Llangollen, and is in the 

 Museum of Practical Geology. It is one of the most 

 instructive specimens which I have hitherto examined. 

 The cardinal process was, however, so much imbedded 

 in the matrix that it could not be developed, so that 

 the deficiency was completed from another example in 

 the British Museum. 

 4. ,, ,, Ideal section or both valves (slightly improved) from the 



figure published by Mr. S. P. Woodward, at p. 233 

 of his ' Manual of the Mollusca.' The letters refer to 

 the same parts in the other specimens. 



