453 
microcephalous new-horn pig , etc. 
as shewing that although in the classical descriptions 1 , the 
mesoderm is not supposed at first to intervene between the 
ectoderm and endoderm in this membrane, nevertheless it does 
thus intrude at all events in such a case as that under considera- 
tion. The mucous membrane is thickest over the tongue, and it is 
here marked by more exuberant folds than elsewhere. 
Such are the principal features of this remarkable specimen. 
Before adding any further notes by way of summarising the 
foregoing remarks, two points deserve attention. 
(1) In searching for rudiments of the mandible, I found that 
the mass of bone marked (? Mandible) in Fig. 18 was in reality not 
part of the cranium as it had first seemed to be, but that it repre- 
sents tissues formed anteriorly to the skull. Between this mass 
and the cranial base, soft tissue containing striated muscle fibres 
intervened and this may possibly represent the external rectus 
muscle of the eye, for a nerve corresponding in position to the 
sixth cranial nerve was seen to arise from the usual situation on 
the bulb. The connexion between the cranium and what I have 
termed the mass of bone, was lateral and not median. The mass 
is to some extent subdivided into upper and lower parts and each 
of these contained a gelatinous substance. From the lower mass, 
some of this jelly-like tissue was removed in an encapsuled state. 
This strongly suggested to me the probability of the nature of the 
gelatinous substance being dental, but microscopic examination 
gave me no aid in ascertaining whether this view were correct or 
not. The lateral attachment of the osseous mass to the undoubted 
1 Robinson in Cunningham’s Text Book of Anatomy, 2nd Edition, p. 23. 
30—2 
