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. Hdge-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. 16.—Naiadites obesa. The largest of the original shells figured by Mr. R. 
Ktheridge, jun., ‘Quart. Journ. Geol. Soc.,’ vol. xxxiv, 1878, pl. 1, fig. 12a. From 
Micaceous Sandstone, Drumsheugh. In the Collection of the Museum of Science 
and Art, Edinburgh. (Page 144.) 
Figs. 17—19.—Naiadites magna, nu. sp. From the Black Band Ironstone, Bank- 
end, Lesmahagow. From the Braidwood Collection of Dr. Hunter. (Page 151.) 
Figs. 20, 20a, 20b.—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.) 
