642 Dr. F. E. Beddard on the Bloio-holes and 



I owe to the kindness of Mr. Chubb, the Curator of the 

 Durban Museum. The authorities of the College of 

 Surgeons were so good as to allow their skilled assistant 

 Mr. Steward to prepare for my use (and for other persons 

 in the future) a complete series of sections of the head. 

 My thanks are tendered to these gentlemen. 



§ The Communication of the Nasal Passages with 

 the Blow-hole, 



In drawings of the blow-holes of this foetus ^^ and in the 

 accompanying letterpress, I have indicated a practically 

 continuous furrow, forming the right and left blow-holes 

 laterally, and consisting in front of a much shallower con- 

 necting region, concerning the actual existence of which I 

 was unable, indeed, to be perfectly certain. There was no 

 doubt, however, about the quite deep right and left blow- 

 holes. I find on examination of my sections that the 

 median region of what is therefore at this stage a single 

 blow-hole is by no means missing ; and that the impression 

 which it gave me — on examining it merely with a lens — as 

 a shallower connecting furrow was correct. For, as a 

 matter of fact, the two nasal tubes, quite distinct from each 

 other until the very edge (in front) of the nasal region of 

 the head, open into and form a perfectly continuous groove 

 extending right round the anterior convexity of the nasal 

 portion of the head — imperfectly shown in the drawings to 

 which I have just referred. The reason why there appeared 

 to me to be a doubt about the matter, when describing the 

 external characters of this foetus, is at once explained by an 

 examination of the sections. There it will be seen that the 

 detached epithelial lining of this region of the blow-holes, 

 which has a rod-like form (as will be explained later), 

 partially blocks the linear orifice and gives it the appearance 

 of a shallow, and even in parts non-existent, groove. 



It wnll be seen from the series of transverse sections, 

 which are arranged in order from in front backwards, that 

 the two nasal passages, right and left, both open into 

 what obviously represents a common chamber, which itself 

 in this young foetus has a single median anterior aperture 

 corresponding exactly to the median part of the combined 

 single blow-hole. As I have partly indicated in the external 

 figures referred to, two furrows lead from the left- and right- 

 hand corners of this median orifice, which are the right and 



* Loc. cif. vol. ii. pt. 4, Oct. 1919, p. 135, text-fig-s. 1-4. 



