SKULL OF A HUMAN FETUS OF 40 MM. 423 



anterior portion of the dentary, and posteriorly terminating in a 

 slender process, as described. Within this medial plate the tooth 

 gutter is well-marked. The condition is very similar to that 

 shown by Low ('09) in his text figure 4. 



CONCLUSION 



From the foregoing brief account of the morphology of the 

 human fetal skull of 40 mm. it will be seen that it presents, at 

 this stage, several unique features. The structure of the parts 

 surrounding the foramen magnum is significant in casting, per- 

 haps, some further light upon the genesis of this interesting region. 

 The presence of a fairly clearly defined neural arch of the occipital 

 vertebra has been dwelt upon, and its interpretation discussed. 

 The finding of a small nodule of cartilage above and in front of 

 the cochlea is, so far as I am aware, a contribution to our knowl- 

 edge of the parts in this area. Other new features are the carti- 

 lagines paraethmoidalis, meatus medii and paraseptalis superior, 

 all of which have been briefly described ; in addition may be men- 

 tioned the lateral and dorsal cranial cartilages, and the paranasal 

 cartilage, lying lateral to the lacrimal duct. 



Finally, I wish to express to Professor McMurrich my sincere 

 appreciation of his kindness in placing at my disposal the mate- 

 rial for this research, and the freedom of the Anatomical Labora- 

 tory of the University of Toronto, as well as of his abundant 

 advice and encouragement. 



Anatomical Laboratory, University of Toronto 

 September, 1913 



