64:6 Dr. F. E. BecUlarJ on the Blow-holes and 



these parts in the Cachalot are Pouchet and Beauregard *, 

 to whose memoir I have had to refer so often in this series 

 of contributions. It would seem that the right nostril 

 undergoes a further differentiation of the large terminal 

 chamber. This clearly closes up in front, except for where 

 it communicates with the exterior in common with the left 

 nostril, in the way in which I pointed out as probable in 

 my account of the external characters of this foetus f. The 

 authors mentioned speak of the ^^ Developpement exagere 

 de la narine droite avec son sinus.^' The sinus is a diver- 

 ticulum of the following tract of the right nasal passage, 

 the anterior dilatation being a specialised pouch opening 

 into the '^ sac de I'event,''' which is the common chamber of 

 both nostrils. 



Posteriorly the two nasal passages open into a larger 

 terminal portion, which is the nasal pharynx. Of these the 

 authors remark that the right nostril is ^' beaucoup plus 

 etroit que la gauche.'^ But in the figure the smaller of the 

 two ("^")| is lettered as the left! It seems to me to be 

 quite likely that variations occur, and that the authors saw 

 examples of both conditions. At any rate, they are equal 

 in my much younger foetus. It is to be noted that this 

 terminal region of the nasal canals presents the appearance 

 in the fully-developed animal of a distinct and large chamber, 

 into which open — as if they were ducts — the two separate 

 nasal passages. Its origin as a mere fusion of these two 

 tubes is not exactly indicated in the adult. 



The left nasal passage has no such specialisation. It is, 

 however, different from the same passage in the young 

 foetus described above, in that it possesses " dans toute son 

 etendue . . . interieurenient un bourrelet saillant.''' This 

 structure is suggestive of the typhlosole of the earthworm's 

 intestine. It also occurs in the lesser Sperm-Whale, Cogia^ 

 where it has been described by Benham §, and later by 

 Danois || and Kernan and Shulte^, whose accounts are not 

 in exact harmony as to several points. It is to be noted, 

 however, that the right nasal passage is dilated along its 



♦ '' llecherches sur le Cachalot," Nouv. Arch. Mus. (3) iv. pp. 1-30. 

 t Ann. Durban Mus. vol. ii. pt. 4, p. IMet seq. 



I Loc. cit. pi. vi. tig'. 3. 



§ " On the Anatomy of Cogia hrevicei^s^,' Proc. Zool. Soc. 1901, vol. ii. 

 p. 107. 



II *' Eeclierches de FAnatomie . . . de Kogia,^'' Arch. Zcol. Exp. (5) vi. 

 (1910). 



^ " Memoranda upon . . . foetal Kogia,^^ Bull. Amer. Nat. Hist. Mus. 

 xxxviii. (1918). 



