570 
Mr, De la Beche andls/ix. Conybeare on 
were supposed to have been the nostrils. We have already stated our 
reasons for doubting whether the contrary evidence, arising from the 
single specimen in which these apertures appeared to be closed 
externally, was quite sufficient to invalidate this supposition. If 
however it should eventually be proved that these openings are actu- 
ally closed in perfect specimens, which, although we have yet failed 
in tracing the fact, may nevertheless not impossibly take place, in 
consequence of the prolongations of the intermaxillary and anterior 
frontal bones folding over them ; (since the common mutilation of 
the extremities of those bones might certainly account for the pre- 
sent exposure of these openings : *) — in that case the narrow slit at 
the fore end of the snout must be the true nostril, and these oval 
foramina must be the openings of the lacrymal into the interior of 
the nasal canal, exposed by this accidental removal of their external 
covering ; a supposition which will agree very well with their place 
in front of their lacrymal bones ; they are represented by dotted 
spaces in the accompanying figures. 
We have now described all the bones of that part of the head 
which is anterior to the orbit, and forms the snout of the animal. 
The frontal part of the head consists of five distinct bones ; the 
middle frontal, H, which extends between the orbits, the anterior 
frontals, h , h , which form the upper anterior portions of the orbit, 
and the two posterior frontals, h\ h\ which by their post-orbital pro- 
cesses h'\ h'\ form the upper and posterior margin of the orbit, 
and complete it by uniting with the jugals, c, c> which form its 
lower part. 
* Since this paper went to press we have seen specimens which decide that this aperture 
was also perforated through the end of the intermaxillary bone, and consequently must 
have been open externally ; the necessary conclusion is, that the appearances in the single 
skull, described by Sir Everard Home, must have been deceptive, and that the only 
objection to considering these apertures as the nostrils is removed. 
