PLATE IX. 



Fig. 1. — Parallelodon cingulatus. Showing the convex right valve, from the Carboniferous 

 Limestone of Castleton. In the Collection of Mr. J. Barnes, of Manchester. (Page 137.) 



Fig. la. — The left valve of the same specimen. 



Fig. 1 b. — The same specimen viewed from above, showing it to be inequivalve. 



Fig. 2. — Parallelodon cingulatus. The flattened left valve. Same locality. My Collection. 

 (Page 137.) 



Fig. 2 a. — The right valve of the same specimen. 



Fig. 3. — Parallelodon cingulatus. A right valve. Same locality. My Collection. (Page 137.) 



Fig. 4. — Parallelodon cingulatus. The type specimen figured by M'Coy. In the Griffith 

 Collection of the Museum of Science and Art, Dublin. (Page 137.) 



Fig. 5. — Parallelodon bistriatus. A fairly perfect specimen from the Carboniferous Limestone 

 of Park Hill, Derbyshire. My Collection. (Page 134.) 



Fig. 5 a. — A portion of the same specimen, magnified to show the ornament. (Page 134.) 



Figs. G, 7. — Parallelodon bistriatus. Two examples of the left valve, Fig. 7 being semi- 

 decorticated, and showing no striae. Same locality. My Collection. (Page 134.) 



Fig. 8. — Parallelodon bistriatus. A right valve. Same locality. My Collection. (Page 134.) 



Figs. 9 and 10. — Parallelodon bistriatus. Two perfect examples of adult specimens. Same 

 locality. Collection of Mr. J. Barnes, Manchester. (Page 134.) 



Fig. 9 a. — The ornament shown on Fig. 9, magnified. (Page 134.) 



Fig. 9 b. — The same shell viewed from above, showing it to be equivalve. (Page 134.) 



Fig. 11. — Parallelodon bistriatus. Said to be the original of M'Coy's figure of the species in his 

 ' Synopsis of the Carb. Foss. Ireland.' In the Griffith Collection of the Museum of Science and 

 Art, Dublin. (Page 134.) 



Fig. 12. — Parallelodon bistriatus. The type of Portlock's figure. In the Collection of the 

 Geological Survey, Jermyn Street. (Page 134.) 



Fig. 13. — Parallelodon Verneuilianus. A fairly perfect example, showing the right valve, from 

 the Carboniferous Limestone of Trey Cliff, Castleton. In the Collection of Mr. "W. F. Holroyd, 

 Manchester. (Page 132.) 



Figs. 14 — 17 '.— Parallelodon Verneuilianus. A series from the Carboniferous Limestone of Little 

 Island, Cork. In the Collection of Mr. J. "Wright, of Belfast. (Page 132.) 



Fig. 17 b. — The shell represented by Fig. 17, seen from above. (Page 132.) 



Figs. 17 a, 17 c— The same shell enlarged. (Page 132.) 



Fig. 19. — Parallelodon squamosus. A right valve from the Carboniferous Limestone of Wetton. 

 In the Collection of the Geological Survey, Jermyn Street. (Page 138.) 



Figs. 18, 20, 21. — Parallelodon squamosus. A series from the Carboniferous Limestone of Settle. 

 In the Burrow Collection of the Woodwardian Museum, Cambridge. (Page 138.) 



Figs. 22, 22 a. — Parallelodon squamosus. — A specimen showing the details of the hinge of a left 

 valve. Same locality and Collection. (Page 138.) 



Fig. 23. — Parallelodon reticulatus. A full-grown example of the left valve. From the Carboni- 

 ferous Limestone of Trey Cliff, Castleton. My Collection. (Page 142.) 



Fig. 24. — Parallelodon reticulatus. A bivalve example, showing the anterior teeth of the hinge 

 of the right valve. Same locality. My Collection. (Page 142.) 



Fig. 25. — Parallelodon reticulatus. A fairly perfect example with both valves. Same locality. 

 My Collection. (Page 142.) 



Fig. 25 a. — The same specimen, viewed from above. (Page 142.) 



