E. B. Tawney—Woodwardian Laboratory Notes. 207 
§ 2. Dentition. 
The teeth of all the Eocene flesh-eaters mentioned in the first 
section, as compared with those of the typical Carnivora, are 
apparently more or less anomalous. There is, as a very general 
rule, nothing exceptional in the form or number of the incisors or 
the canines. But the peculiarity in the arrangement, number, and 
form of the molar teeth, both upper and lower, has been the great 
stumbling-block in the way of comparative anatomists, some of 
whom, as we have seen, have tried to cut the Gordian knot by 
removing the majority of them to the group of the Didelphia. 
Amongst those who argue in favour of their location in the order of 
the Carnivora, the diversity of opinion with regard to the exact 
position they should occupy in that order shows the difficulty of 
affiliating them with any of the existing families. As we shall try 
to establish in this section that the peculiarities in the dentition of 
the Eocene Carnivores can be most satisfactorily explained on the 
hypothesis of its gradual modification from that of some primitive 
Mammal, the nearest approach to which is the Insectivorous 
Gymnura, now living in the islands of Malacca and Sumatra, we 
shall begin with a brief notice of the salient points in the dental 
conformation of this most generalized Mammal known to us. 
(To be continued in our next Number.) 
T1].—Woopwarpian Lazoratory Notres.—Norta Wares Rocks. 
By E. B. Tawney, M.A., F.G.S., 
Woodwardian Museum, Cambridge. 
N the following notes we propose to collect descriptions of some 
of the igneous rocks of N. Wales founded on the collections 
made by the late Prof. Sedgwick many years ago. It is hoped that 
it may be of interest to readers of this Macazinz, as many students 
turning their attention to rocks find a want of information in text- 
books concerning precise localities in Britain for the occurrence of 
many interesting types. Following Sedgwick’s steps may help 
them partly to what they require, while the microscopical analyses 
appended will doubtless prove an aid to beginners, besides being 
a definite record, as far as it goes, of some types of Welsh rocks. 
In the Woodwardian Museum are deposited rich collections made 
by Sedgwick in travels through N. Wales, chiefly from 1831-6, 
illustrating not only the sedimentary formations, but containing a 
copious selection of the igneous rocks—made, too, at a time before 
there was any Geological Survey Map to act as a guide to localities 
where things of interest might be expected. These were all num- 
bered by him according to the district where they were collected, 
and from his Catalogue we obtain the locality, as far as the imperfect 
topographical map with which he worked allowed it to be indicated, 
for the Ordnance Map was not then published. [The numbers in 
brackets will be those of his Catalalogue, and they are given to 
distinguish his from later additions. ] 
Owing to recent advances in Petrology due to the microscope, 
