as indicative of the Ago of the Animal. 
345 
Fig. iZ* 
value. When removed into other districts where they can live on 
good grass-land, and have " manger food," these animals are how- 
ever profitable both for breeding and 
other purposes. They nevertheless 
require great care ; but, imtli care, 
"broken-mouthed" ewes are not un- 
frequently kejit for breeding purposes 
until they become ten, twelve, or 
fifteen years old, in Leicestershire and 
other counties. There is this important 
difference, however, between the old 
sheep of Leicestershire and the ^' crones^' 
of Norfolk, namely, that in the one in- 
stance the incisors have been gradually 
worn away, while in the other they have 
been prematurely forced out or broken 
off, and broken incisor often leads to 
displacement of the other teeth near it, sometimes too lacerating 
the dental pad, and even working its way through the substance 
of this pad to the bone. Such things require the especial attention 
of the purchaser of Norfolk " crones." 
To return to the cutting of the fourth pair of permanent inci- 
sors. These teeth succeed the third pair at an interval of about 
nine months, which brings the sheep of early dentition to three 
years, and of late dentition to three years and six months. The 
following figure gives the appearance 
of the mouth at any intermediate 
period, say three years and a quarter. 
All the permanent teeth are now in 
their place, the pair last cut being 
marked 4, 4 (fig. 44). It is not, 
however, to be supposed that all 
sheep will be "full mouthed" even 
at three years and a half. There 
are some exceptions, for greater ir- 
regularity attends the time of cutting 
the fourth than any of the other 
pairs. Still allowing for occasional 
cases where these teeth are not in the 
mouth until four years of age, we 
see that even with these late excep- ° ^° 
* Fig. 43. Front view of the lower jaw at two years and a half, showing tliat 
the third pair of permanent teeth, 3, 3, are in situ. Natural size. 
_t Fig- 4^- Front view of lower jaw at three years and a quarter, the fourth 
pair of incisors, 4, 4, being cut, thus completing dentition. The central pair give 
evidence of slight wear, and from rising in the socliets an open space is seen 
between their fangs. Natural size. 
Fig. 44 .t 
