440 
THE GEOLOGIST. 
specimens would, however, be required in order to warrant any decided statement on 
these subjects. It is ])ossible, 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 my present impression is that it tends rather toward the genus Hylono- 
mus. It may possibly be a liuk of connection between the Microsauria and the Arcbe- 
gosauria." 
Besides the foregoing species, Mr. O. C. Marsh added, in 1861, a new 
animal to the Joggins reptilian fauna, the Eosauims 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 vertebrse of Eosaums 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 vertebrse were caudal, as supposed by Mr. ^larsh, 
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, Xylohius 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-measm-es of Nova Scotia, therefore, while marine conditions are absent, 
there are ample evidences of fresh-water or brackisb-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. ^Vhen 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, we 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 find 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 stratigraphical 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. 
