PLATE XII. 



Fig. 



1. Strophalosia Goldfussi, Miinster. Cast, large valve, natural size. Ryhope Field- 



House Farm. 



2. — — Cast, small valve, natural size. Ryhope Field- House 



Farm. 



3. — — Cast, large valve, natural size : a, Cardinal and valvular 



muscular sears confluent. Humbleton Hill. 



4. — — Cast, large valve, natural size. Ryhope Field-House Farm. 



5. — — Representation (copied from a gutta-percha cast of fig. 9) 



of inner surface of small valve, showing boss or cardinal 

 muscular fulcrum {a) ; dental sockets {h) ; median 

 plate (c) : impression of vein connecting the reniform 

 lobes with the medio-cardinal region {d) ; reniform 

 lobes {e) ; posterior division of the valvular muscles (/) ; 

 anterior division of the same (y). 



6. , — — ' Cast (natural size) of small valve, and area of large valve 



Ryhope Field-House Farm. 



7. — — Testiferous specimen. Same view (natural size) as last : 



a, area ; b, deltidium. Ryhope Field-House Farm. 



8. — — Cast, same view (natural size) as last. Humbleton Hill. 



9. — — Cast, natural size, showing depressions of the teeth of the 



large valve {a). Humbleton Hill. 

 10 — — Cast of a young specimen. Humbleton Hill. 



11. — — Cast (nearly twice the natural size) of a young specimen. 



Ryhope Field-House Farm. 



12. — — Gutta-percha cast, of the area {a), and deltidium {b) of the 



large valve. Original from Ryhope Field-House Farm. 



13. Strophalosia excavata, Geinitz. Gutta-percha cast of the large valve, natural 



size, showing the spines. Original from Dalton-le-Dale. 



14. — — Cast, small valve. Humbleton Hill. 



15. — — Gutta-percha cast of small valve (crowded with spines), 



and areas. Dalton-le-Dale. 



16. — — Cast, small valve. Humbleton Hill. 



17. — — Gutta-percha cast of area of both valves : a, large valve; 



c, small valve. Original from Dalton-le-Dale, 



18. Strophalosia Morrisiana, X27?y. Small valve (natural size) of a testiferous specimen. 



Tunstall Hill. 



(The spines are preserved on the large valve only). 



