512 



AIR-BREATHERS IN THE COAL. 



Fig. 561. 



[Ch. XXV. 





&& 



a. Pupa vetusta. Dawson. Nat. size. 



&. The same, magnified. 



o. View of the depressed apex. 



d. Surface stria?, magnified 50 diam. 



e. Surface strise, of the recent English Pupa 



juniperi for comparison, magnified 50 

 diam. 



f. Microscopic structure of the shell, showing 



hexagonal cells, magnified 500 diam. 



of coal. This lower bed is an underclay V feet thick, with stigmarian 

 rootlets, and the small land-shells occurring in it are in all stages of 

 growth. They are chiefly confined to a layer about 2 inches thick, 

 and are unmixed with any aquatic shells. They were all originally 

 entire when imbedded, but are most of them now crushed, flattened, 

 and distorted by pressure ; they must have been accumulated, says 

 Dr. Dawson, in mud deposited in a pond or creek.* The late Prof. 

 Quekett, to whom I submitted the first specimen found in 1852 for 

 microscopical examination, observed that the surface striae, on being 

 magnified 50 diameters, d, fig. 561, presented exactly the same appear- 

 ance as a portion corresponding in size to the common English Pupa 

 juniperi (e, fig. 561), and a cross-section of the fossil shell (/, ibid.) 



Kg. 562. 



a. Nat. size. 



Xylobius Sigillarice, Dawson. Coal, Nova Scotia. 

 &. Anterior part, magnified. c. Caudal extremity, magnified. 



presents the hexagonal cells magnified 500 diameters, so like those of 

 the recent Pupa that a figure of the latter is unnecessary.! 



* Dawson, Air-Breathers of the Coal. 

 \ Quart. GeoL Journ. 1853 vol. ix. p. 



