PLATE XVI. 



Fig. 1. — Schizodus Earii. A left valve from tlie Upper Coal-measures, Kansas, 

 U.S.A. My Collection. (Page 214.) 



Fig. 1 a. — Schizodus Earii. The hinge of the same specimen, figured to give 

 an idea of the typical hinge of the genus as developed in a large example. 

 x, anterior tooth ; ?/, bifid cardinal tooth ; z, elongate posterior lateral tooth. 

 (Page 214.) 



Fig. 2. — Schizodus Pentlanclicus. The interior of a right valve, with the hinge- 

 teeth and muscle-scars. From the Calciferous-sandstone series, Woodhall, Water 

 of Leith. In the York Museum. (Page 217.) 



Fig. 3. — Schizodus Pentlanclicus. The hinge of fig. 7 ; a left valve with, a, the 

 anterior tooth ; h, the cardinal tooth ; c, the posterior lateral tooth. Same 

 locality and Collection. (Page 217.) 



Fig. 4. — Schizodus Pentlandicus. The hinge-plate of a right valve ; a, anterior 

 tooth ; b, cardinal tooth ; c, posterior lateral tooth. From the Calciferous-sand- 

 stone series of Pianderstone, Fife. My Collection. (Page 217.) 



Fig. 5. — Schizodus Pentlanclicus. A right valve. Same locality. My Collec- 

 tion. (Page 217.) 



Figs. 6 and 7. — Schizodus Pentlandicus. A right and left valve. From Wood- 

 hall, Water of Leith. In the York Museum. (Page 217.) 



Fig. 8. — Schizodus Pentlandicus. A left valve from Randerstone, Fife. My 

 Collection. (Page 217.) 



Fig. 9. — Schizodus Pentlandicus. A right valve from the roof of the Coopers- 

 eye Coal, Scremerston, Northumberland. In the Collection of the Woodwardian 

 Museum, Cambridge. (Page 217.) 



Fig. 10. — Schizodus axiniformis. A cast, the type specimen of Sowerby's 

 Donax (?) sulcata. From the Pennystone Ironstone, Coalbrookdale. In the British 

 Museum (Nat. Hist.), Geol. Department. (Page 219.) 



Fig. 10 a. — Schizodus axiniformis. The type specimen viewed from above. 

 (Page 219.) 



Fig. 11. — Scliizodus axiniformis. A very large and fine example, semi- 

 decorticated. From the Redesdale Ironstone. My Collection. (Page 219.) 



Fig. 11a. — Scliizodus axiniformis. The same specimen viewed from above. 

 (Page 219.) 



Figs. 12 and 13. — Schizodus axiniformis. Two other specimens exhibiting 

 slight differences in the contour of the posterior extremity. Same locality. My 

 Collection. (Page 219.) 



Fig. 14. — Schizodus axiniformis. A right testiferous valve. Same locality. 

 My Collection. (Page 219.) 



Fig. 15. — Schizodus axiniformis. A right testiferous valve. Same locality. 

 My Collection. (Page 219.) 



