440 



THE GEOLOGIST. 



specimens would, however, be required in order to warrant any decided statement on 

 these subjects. It is possible, as suggested by Professor Owen, that the affinities of the 

 animal may be with Archegosaurus rather than with any of the other Coal reptiles ; but 

 I confess that tny present impression is that it tends ralher toward the genus Hylono- 

 mus. It may possibly be a link of connection between the Microsauria and the Arche- 

 gosauria." 



Besides the foregoing species, Mr. O. C. Marsh added, in 1861, a new 

 animal to the Joggins reptilian fauna, the Eosaurus Acadianus, — a species 

 founded on two large biconcave vertebrae, resembling, in many respects, 

 those of Ichthyosaurus, and of which we have already given a notice in 

 this magazine. 



" The vertebrae of Eosaurus have been fully and ably described by Mr. Marsh in Silli- 

 man's Journal. Agassiz and Wyman regard their affinities as enaliosaurian. Huxley 

 suggests the possibility, founded on his recent discovery of Anthracosaurus Russelli, 

 that there may have been labyrinthodont batrachians in the Coal period with such ver- 

 tebrae. However this may be, if the vertebrae were caudal, as supposed by Mr. Marsh, 

 since they are about 2^ inches in diameter, they would indicate a gigantic aquatic rep- 

 tile, furnished with a powerful swimming tail, and, no doubt, with apparatus for the cap- 

 ture and destruction of its prey, comparable with that of Ichthyosaurus." 



Dr. Dawson next fully describes and discusses the conditions of life and 

 habits of the invertebrate air-breathers, the Pupa vetusta, and the gully- 

 worm or millipede, Xylobius sigillarice. In his concluding remarks he at- 

 tempts to reconcile many of the anomalies seemingly presented by the 

 organic remains of the coal strata. We have already trenched too largely 

 on our space to follow the Doctor through this portion of his excellent 

 pamphlet, but there is one passage we may well transcribe : — 



" In the coal-measures of Nova Scotia, therefore, while marine conditions are absent, 

 there are ample evidences of fresh- water or brackish -water conditions, and of land-sur- 

 faces suitable for the air-breathing animals of the period. Nor do I believe that the 

 coal-measures of Nova Scotia were exceptional in this respect. It is true that in Great 

 Britain evidences of marine life do occur in the coal-measures ; but not, so far as I am 

 aware, in circumstances which justify the inference that the coal is of marine origin. 

 Alternations of marine and land remains, and even mixtures of these, are frequent in 

 modern submarine forests. When we find, as at Fort Lawrence in Nova Scotia, a mo- 

 dern forest rooted in upland soil forty feet below high-water mark, and covered with mud 

 containing living Tellinas and Myas, w r e are not justified in inferring that this forest 

 grew in the sea. We rather infer that subsidence has occurred. In modern salt marshes 

 it is not unusual to mid every little runnel or pool full of marine shellfish, while in the 

 higher parts of the marsh land-plants are growing ; and in such places the deposit formed 

 must contain a mixture of land-plants and marine animals with salt grasses and herbage 

 — the whole in situ." 



The above paragraph is important, because these considerations are in- 

 tended to explain the apparently anomalous associations of coal-plants with 

 marine fossils ; and there are, perhaps, no other arguments of weight that 

 can be adduced in favour of the marine origin of coal, except such as the 

 Doctor asserts to be based on misconceptions of the structure and mode of 

 growth of sigillaroid trees, and of the strati graphical relations of the coal 

 itself. To this he adds a judicious and significant reservation, fully in 

 accordance with the opinions we have ourselves long since expressed, and 

 while he maintains the essentially terrestrial character of ordinary coal 

 and of its plants, he admits that cannel coals and earthy bitumen present 

 evidence of sub-aquatic deposition. 



Full as is this notice, we have not taken all the cream off the milk of 

 Dr. Dawson's book. We can assure our readers there is abundant fare 

 still left for its readers. 



