148 Mr. G. Krefft on the Dentition of Thylacoleo carnifex. 
The above notes were taken from living specimens. 
It would be interesting to know more than is known at pre- 
sent about the distribution of the British Ephemeride. In 
Dorset and on Dartmoor Potamanthus erythrophthalmus is the 
commonest of the genus, whilst P. marginatus is the most fre- 
quent in the Cambridge district. On the Dart Baétis montana 
predominates, but B. lutea at Little Bridy, Dorset. At this last 
place, too, Cloéon Rhodani outnumbers C. bivculatum; but at 
Blandford, in the same county, aud at Cambridge the converse 
obtains. From this it would appear that P. erythrophthalmus 
and C. Rhodani are better fitted to inhabit swift streams than 
P. marginatus end C. bioculatum. 
XXV.—On the Dentition of Thylacoleo carnifex (Ow.). 
By Grrarp Krerrt. 
[Plate XI.] 
To the Editors of the Annals and Magazine of Natural History. 
GENTLEMEN, 
In the December Number of your Journal you figure a tooth 
which is supposed by Prof. M‘Coy to be the hitherto unknown 
canine of Thylacoleo carnifex, because it was discovered “ with 
part of the lower jaw and teeth of Nototherium Mitchelli, on 
which it had probably been feeding.” I do not think the find- 
ing of such a tooth in proximity with a Nototherium’s teeth is 
sufficient proof that it belonged to a Thylacoleo, the more so as 
the huge canine of that animal had never been known before— 
and never will be known, because the Thylacoleo carnifex was 
not furnished with canine teeth, and the dental series (in the 
lower jaw at least) ended in a pair of incisors, from which fact 
I venture to conclude (guided by the analogy furnished by the 
dentition of our living Marsupials with two lower incisors, the 
wombat excepted) that the upper jaw contained the usual six 
incisor teeth, and that if it ever possessed a canine it must 
have been a very small one, corresponding to the diminished 
tooth found in Hypsiprymnus and Phalangista. 
The tooth described by Prof. M‘Coy is not referable to Thy- 
lacoleo ; and the shape of its crown proves it at once to be an 
incisor, not a canine, and most likely the (incisor) tooth of the 
animal with the remains of which it was discovered. Prof.OQwen 
(who long ago expressed his opinion to the effect that the dental 
series of the lower jaw of Thylacoleo would probably end in a 
pair of incisors) has given us a full description of the teeth of 
this animal, to which I have nothing to add, except that, with 
the scanty material at my disposal, I have ventured to recon- 
