499 
number of hyzenas’ bones in the same cavern; and without denying 
to these few lions their lion’s share in the work of killing their prey 
and eating the flesh, I must claim the bones as the perquisite of their 
more ossifragous brethren, and demand justice to the hyzenas, as 
the chief, I do not say the exclusive, agents in dragging them to 
their dens. 
The proportion of teeth in the cave of Kirkdale indicated one 
lion to nearly 100 hyenas. 
REPTILES. 
Professor Owen, in a recent paper on the teeth of the Labyrintho- 
don (Mastodonsaurus of Jaeger), a genus common to the keuper 
of Germany and to the lower sandstone of Warwick and Leaming- 
ton, has added another example to the many before produced by 
him, of the immense importance of microscopic odontology in geo- 
logical investigations. 
Two years have scarcely elapsed, since, by the application of this 
infallible test, he at once transferred the supposed reptile Basilo- 
saurus of Virginia to a genus allied to the Dugongs in the class of 
Mammals; and as if in recompense for this abduction from the fa- 
mily of Reptiles, he has now, by the same microscopic test, removed 
even the supposed approximation in the form of the teeth of the 
Mastodonsaurus to that of a Mammal, and shown it to be nearer 
that of Ichthyosaurus than of any other animal. Professor Jaeger 
had already shown, by the basilar bones of the head, that his Masto- 
donsaurus was a huge Batrachian reptile allied to the Salamanders, 
and its teeth, not yet submitted to microscopic examination of their 
transverse section, presented no apparent peculiarity of internal 
structure ; it was reserved for the microscope of Owen to discover 
within this tooth a condition of cerebriform convolutions or laby- 
rinthoid gyrations, hitherto unknown in the entire animal kingdom ; 
and on this just ground he substitutes the characteristic name La- 
byrinthodon for that of Mastodonsaurus, which implied affinities 
that have no existence. 
The fang of the tooth of the Ichthyosaurus offers the only known 
approximation to the plan of that of the Labyrinthodon, but ona 
more simple scale, and had been hitherto considered the most com- 
plex condition of dental structure in the family of Reptiles; in both 
these animals the external layer of cement is inflected inwards to a 
certain distance from the circumference towards the centre in 
straight and vertical folds at pretty regular intervals, which are oc- 
cupied by dentine radiating from the interior of the tooth; but in 
the tooth of Labyrinthodon, this dentine, or ivory, is composed of 
calcigerous tubes 7z/55th of a line in diameter, radiating and con- 
verging with primary curvatures and secondary undulations in a 
manner unexampled in the history of dentition. This gigantic Ba- 
trachian prototype of the Bull Frog, Mr. Owen has discovered to 
be the author of the footsteps ascribed to the so-called Chirothe- 
rium. Teeth of two smaller species of Labyrinthodon have been 
found by Dr. Lloyd in the sandstone of Warwick, and although no 
