PLATE VIII. 



Fig. 1. — Modiola Jenkinsoni. The type specimen of M'Coy's Lithodomus 

 Jenkinsoni, from the Limestone of Lowick, Northumberland. In the Wood- 

 wardian Museum, Cambridge. The shell is almost entirely absent. (Page 71.) 



Figs. 1 a, 1 b. — The same specimen viewed from above and from the front. 



Fig. 2. — Modiola Jenkinsoni, another specimen from the same locality, showing 

 the adductor scar and the pallial line. (Page 71.) 



Fig. 3. — Modiola Jenkinsoni. A testiferous example from the Carboniferous 

 Limestone of Killogunra, Killala, Ireland. Same collection. (Page 71.) 



Fig. 4. — Parallelodon squamifer. A perfect example from the Carboniferous 

 Limestone of Settle. In the Burrow Collection of the Woodwardian Museum, 

 Cambridge. (Page 130.) 



Figs. 4 a, 4 b. — The same specimen viewed from above and in front. 

 (Page 130.) 



Fig. 5. — Parallelodon squamifer. The type specimen of Modiola squamifera, 

 Phillips, from Bolland. In the Gilbertson Collection of the British Museum 

 (Natural History), South Kensington. (Page 130.) 



Fig. 6. — Parallelodon squamifer. A left valve from the Carboniferous Lime- 

 stone of Settle. Collection of Geological Survey, Jermyn Street. (Page 130.) 



Fig. 6 a. — The same valve, showing the elongate teeth of the posterior parts of 

 the hinge-plate. (Page 130.) 



Fig. 7. — Parallelodon squamifer. A right valve, in the same Collection, from 

 Settle, showing the posterior part of the hinge-plate. (Page 130.) 



Fig. 8. — Parallelodon squamifer. A left valve, from the Burrow Collection of 

 the Woodwardian Museum, Cambridge, from the same locality, showing radiating 

 marking towards the posterior inferior part of the shell. (Page 130.) 



Fig. 9. — Parallelodon obtusus. — A cast of the interior of a right valve, showing 

 the posterior part of the hinge. From the Carboniferous Limestone of Park 

 Hill, near Longnor, in the Collection of the Geological Survey, Jermyn Street. 

 (Page 167.) 



