202 Dr Hisserr on the Limestone of Burdiehouse, 
nection. In fact this labour is only in progress. The Royal 
Society of Edinburgh have transmitted to M. Acassiz as many 
of the specimens from the collection as he wished to examine, 
in order to be illustrated in his work; and it is to be hoped that 
more important relics will still turn up during the process of 
quarrying. The details, therefore, of which this memoir must 
necessarily be deficient, will no doubt be in the course of time 
supplied. 
From another source, however, M. Acassiz has obtained 
most important information relative to the sauroid fish of Bur- 
diehouse. After leaving Edinburgh in company with Dr Bucx- 
LAND, these gentlemen visited many of the public museums of 
Great Britain, among which was that of Leeds, where they found 
the specimen of an entire head of a fossil animal, obtained from 
the coal-fields of Yorkshire, which, from the teeth and other 
bones, was ultimately referred to the same undescribed genus of 
sauroid fish. 
Having obtained access to this great prize, M. Acassiz was 
then enabled, with advantage, to compare the imperfect relics of 
Burdiehouse, first, with the entire head from the Leeds Mu- 
seum; and, secondly, with a large specimen of the recent Lepi- 
dosteus Spatula, preserved in the British Museum. 
After M. Acassrz had, by these various comparisons, esta- 
blished the fact, that the teeth, and certain other osseous remains 
of Burdiehouse, belonged to a sauroid fish rather than to a sau- 
roid reptile, he considered it as a new genus to which he gave 
the name of Mrcaticnruys; and to the species found at Bur- 
diehouse (the first which he had seen), he added the name of 
Megalichthys Hibberti. 
NOTES TO SECTION X. 
Under ordinary circumstances, I might have declined the honour thus rendered 
me. If I have accepted it, the following reasons may be assigned : 
M. Acassiz had expressed some little apprehension for any pain which he might 
inflict in setting me right upon a question regarding which I had publicly expressed 
