PLATE XIX. 



Figs. 1 — 7. — Naiadites obesa. A series of weathered specimens showing the 

 structure of the hinge, and the pits for the anterior muscles. From the 

 Calciferous- Sandstone Series of Fife. My Collection. (Page 144.) 



Fig. 8. — Naiadites obesa. A specimen of a right valve, showing the emarginate 

 posterior border. From Oakbank Quarry, Midcalder. My Collection. (Page 144.) 



Figs. 9 and 10. — Naiadites obesa. — Two right valves from the Calciferous Sand- 

 stone-Series of Kilrenny Mill, Fife. My Collection. (Page 144.) 



Fig. 11. — Naiadites obesa. A left valve. From the same locality. My Collec- 

 tion. (Page 144.) 



Figs. 12 — 14. — Naiadites obesa. The originals of Mr. R. Etheridge's, jun., 

 Anthracoptera tumida. From the Shale above the " Brownstone " portion of the 

 Boness Lower Ironstone. Edge-Coal Series. Collection of the Geological Survey 

 of Scotland, Edinburgh. (Page 144.) 



Fig. 15. — Naiadites obesa. A left valve with the shell removed in front, 

 showing the tubercles representing the pits for the muscle-scars. Kilrenny Mill. 

 My Collection. (Page 144.) 



Fig. 10. — Naiadites obesa. The largest of the original shells figured by Mr. R. 

 Etheridge, jun., ' Quart. Journ. Geol. Soc.,' vol. xxxiv, 1878, pi. i, fig. 12 a. From 

 Micaceous Sandstone, Drurnsheugh. In the Collection of the Museum of Science 

 and Art, Edinburgh. (Page 144.) 



Figs. 17 — 1 ( .). — Naiadites magna, n. sp. From the Black Band Ironstone, Bank- 

 end, Lesmahagow. From the Braidwood Collection of Dr. Hunter. (Page 151.) 



Figs. 20, 20 a, 20//. — Naiadites magna. Three views of a large example, 

 showing the typical cast of the anterior end and the sinuated folding at the poste- 

 rior inferior angle. From the same locality and Collection. (Page 151.) 



Figs. 21, 21 a. — Anthracomya subcentralis. Two views of a typical specimen, 

 showing the gibbosity of the shell. From the original locality, South Wales. In 

 the Collection of the Geological Survey, Jermyn Street. (Page 109.) 



