454 
Dr Duckworth , Description of a 
cranium corresponds to a point immediately in front of the 
emergence of the fifth cranial nerve. In spite of the failure to 
provide an absolutely certain diagnosis of the nature of this bone- 
substance, I feel sure that it represents an aborted imperfect facial 
skeleton. 
It remained to endeavour to identify the cranial nerves and 
a careful re-examination of the encephalon enabled me to make 
the sketch represented in Fig. 20. The cranial nerves which 
could be identified were 
Fig. 20. 
(a) The fifth (with sensory and motor divisions and an 
aberrant anterior division which looked rather like the fourth 
nerve : but in the absence of the orbit and its contents, as well as 
of the midbrain, I consider this filament to belong to the fifth). 
(b) A nerve which I can only identify with the sixth ; it 
seemed to go to the muscle immediately behind the osseous mass 
to which reference has been made in the preceding paragraph. 
(c) The seventh and eighth together. 
(d) The ninth, tenth and eleventh together. 
( e ) The twelfth nerve. 
In reviewing the general character of this microcephalous pig, 
one sees that for some reason or other, the neural groove had 
never extended far enough forward to provide for the formation of 
the first and second cerebral vesicles, or else, that the latter had 
been formed, but that in the process of flexion of the nervous 
tube, they had become detached and had disappeared. I incline 
to the former of these two views, because those parts of the brain 
which had actually been formed, were smaller than usual, so that 
failure of the growth-power of the anterior part of the neural 
groove is suggested. 
Secondly, the disturbance has been quite a local one and this 
statement is based upon the examination of the tissues and organs 
in general, as well as on that of the central nervous system in 
particular. Regarded as a case of microcephalus, this example 
falls into the category of those in which there is no diminution or 
arrest of development in the spiral cord (i.e. no micro-myelia). 
