SUPPLEMENT, PLATE XLII. 



cornish lower silurian. 

 Fig. 

 1,2. Strophomena grandis,$ov?. In a light grey quartzite, Cam Gorran, Cornwall. 2. A restored 



figure from an impression of exterior of ventral valve taken in gutta 



percha. (P. 329.) 



3. „ ,, Portion of exterior of dorsal valve. (P. 329.) 



4. „ „ Longitudinal section of both valves. (P. 329.) 



5. „ „ Fragment of internal cast of ventral valve. (P. 329.) 



6. ,, „ Fragment of internal cast of dorsal valve. (P. 329.) 



Figs. 1 to 6 from specimens in the Penzance Museum. 



7. 7 a. Orthis calligramma, var. Distorted external impressions. Cam, Gorran Haven. Penzance 



Museum. (P. 329.) 



8 — 10. ,, ,, 8. Internal cast of ventral valve. 9. External surface of shell enlarged. 



10. Interior of ventral valve. Gorran Haven. Museum of the School of 

 Mines, London. (P. 329.) 



11, 12. ,, scotical M'Coy, sp. From impressions of dorsal valve in dark grey limestone. Gorran 



Haven. Penzance Museum. (P. 329.) 



13. ,, sp. ? Cam of Gorran Haven. Mus. Geol. Soc. Ed. 



14, 15. ,, Berthoisi, var. cornubiensis, Tromelin. This is probably the shell referred to by Prof. 



M'Coy to his O. turgida. Caerhayes. 14. Internal cast, Truro 

 Museum. 14 a. Interior of dorsal valve taken in gutta percha from 

 internal cast, fig. 14. 15. Fragment showing exterior sculpture. 

 (P. 329.) 



16 — 25. „ Budleighensis. 16, 17. Large very flat dorsal valves in a light grey quartzite, Cam near 



Gorran Haven, and presented by Mr. Peach to the Edinburgh Geol. 

 Society. 17. The same in a yellowish-grey quartzite in the Penzance 

 Museum. These are probably the specimens referred by M'Coy to his 

 Orthis retrorsistria, and to some very flat forms of which it bears much 

 resemblance. 16 a, b. Enlarged. 18, 20. Ventral valve. Gorran 

 Haven and Gerran Bay. Penzance Museum. 19, 25. Internal casts of 

 ventral valve. 21. Dorsal valve. Gerran Bay. 23, 24. Dorsa valve 

 and internal casts of dorsal and ventral valves. 23 a, b. Enlarged. 

 Gorran Haven. Museum of School of Mines, London. (Pp. 329, 358.) 



26. ,, testudinaria, Dalman type. Specimen from Borenshult in Ostrogothia, Stockholm, 



Sweden, and lent by State Museum. Figured here for comparison 

 with British specimens. (P. 359.) 



