THE OLDEST AIR-BREATHERS 269 



skull of Baphdes planiceps was derived. It is a laminated bed, 

 sometimes hard and containing much ironstone, in other 

 places soft and shaly, but always black and carbonaceous, 

 and often with layers of coarse coal, though with few fossil 

 plants retaining their forms. It contains large round flat 

 scales and flattened curved teeth, which I attribute to a fish of 

 the genus Rhizodus, resembling, if not identical with, R. 

 landfer, Newberry. With these are double-pointed shark-like 

 teeth, and long cylindrical spines of a species of Diplodust 

 which I have named D. acinacesl There are also shells of 

 the minute Spirorbis, so common in the coal measures of 

 other parts of Nova Scotia, and abundance of fragments of 

 coprolitic matter, or fossil excrement, sometimes containing 

 bones and scales of fishes. 



It is evident that the " Holing stone " indicates one of 

 those periods in which the Albion coal area, or a large part of 

 it, was under water, probably fresh or brackish, as there are no 

 properly marine shells in this, or any of the other beds of this 

 coal series. We may then imagine a large lake or lagune, 

 loaded with trunks of trees and decaying vegetable matter, 

 having in its shallow parts, and along its sides, dense brakes of 

 Calamites, and forests of Sigillaria, Lepidodendron, and other 

 trees of the period, extending far on every side as damp pesti- 

 lential swamps. In such a habitat, uninviting to us, but no 

 doubt suited to Baphetes, that creature crawled through 

 swamps and thickets, wallowed in flats of black mud, or swam 

 and dived in search of its finny prey. It was, in so far as we 

 know, the monarch of these swamps, though there is, as 

 already stated, evidence of the existence of similar creatures of 

 this type quite as large in other parts of the Nova Scotia coal 

 field. We must now notice a smaller animal belonging to the 

 same family of Labyrinthodonts. 



1 " Supplement to Acadian Geology," pp. 43 and 50. These fishes are 

 now known under the generic name Leptacanthus. 



