19 
an indispensable part of the literature of this subject. A 
fine skull, 15 in. b}- 12 in., exhibiting the under or palatine 
aspect, with numerous broken teeth in two rows (many of the 
teeth presenting radiating involutions of the pulp cavitj^) 
furnished the new genus Arithracosaurus. To this genus were 
also referred a vertebra and rib found in the same bed in the 
Airdrie coalfield, which had previously furnished the skull. 
These last remains are identical with those attached to the 
Low Moor fossil, and from our recent discovery we shall be 
in a position to decide that they are quite distinct from the 
type skull of anthracosaurus (now preserve'd in the Museum 
of Practical Geolog}'). A number of interesting specimens, 
comprising a land mollusk (Pupa vetusta), a chilognathous 
m3Tiapod {X?/Iohi>(s) , and various reptilian remains, have 
been found at difierent times by Dr. Dawson within hollow 
trunks of sigillaria, in the coal-measures of Nova Scotia. 
These have been described by Professor Owen (Geo!. Journal, 
1860). Although the American specimens unquestionably 
are nearly related to some of those already mentioned, the 
disastrous and discreditable strife carried on by our two 
greatest comparative anatomists renders them unwilling to 
cite each other's labours, and a satisfactorj^ resume of the 
whole question seems at present impossible. A new amphi- 
bian (pholidogaster) in fair preservation, and throwing much 
Kght upon our subject, may be seen in the British Museum. 
A description and figure by Professor Huxley will be found 
in the Geological Journal (1862). Pholidogaster exhibits 
well ossified vertebrae and an arrangement of ventral scales 
very like archegosaurus. Messrs. Hancock and Atthey have 
also found in the Newcastle coalfield numerous remains of 
labyrinthodonts, one of which, named b}^ them Pteroplax 
cornuta, is nearly allied to the present form. Dr. Young and 
Mr. Thomson have added various new species from the neigh- 
bourhood of Glasgow, fuller details of which are promised. 
