jVasal Passaijes of the Cachalot. 647 



lengtlj, and opens anteriorly in common witli left mncli in 

 tlie same way as these tubes are related in Physeter. It is 

 unnecessary to ^^o into further details of comparison, as the 

 object of this paper is the description of the structure of a 

 fcjctus of Physeter. x\nd I have not noted that this foetus 

 presents a closer likeness to the adult Cogia than it does to 

 the adult Physeter. 



Messrs. Pouchet and Beauregard supply in their memoir 

 a very useful sketch of a transverse section^, which throws 

 some light upon the different proportions of the regions of 

 the blow-hole in their specimen and in that which I describe 

 here. The section in question is of a young male animal 

 with a head of 1'30 M. in length. It shows the much 

 greater extent in this, of course, practically adult whale of 

 the dilated region of the right nasal passage, which their 

 measurements allow me to compare with the corresponding 

 ones of my ftietus. The section is taken at a distance of 

 40 cm. from the snout, i. e., occupying a position at about 

 the end of the first third of the head. The dilated chamber 

 in the foetus is very much shorter. It ceases to be dilated 

 at about the 24th slide, out of a total, which embrace the 

 head, of 180 odd slides. Thus the two nasal passages are 

 not very different in size after the first seventh or eighth of 

 the total length of the head. It is clear, therefore, that a 

 great deal of growth takes place anteriorly to this point as 

 the foetus advances towards maturity. I shall haA^e to refer 

 to this figure again in considering the internasal cartilage 

 and the position of the spermaceti mass in the young whale. 



§ Cartilages of Blow -holes and Nasal Passages, 



The anterior median cartilage of the head — ethmoid, 

 rostral, fused trabeculae cranii, or whatever we may term 

 it — has anteriorly, in this foetus, no connection at all with 

 the cartilages which partly envelop the nasal tubes. It is a 

 rounded rod (in transverse section) which terminates ante- 

 riorly in quite close connection with the epidermis, being 

 prolonged there in a straight line from the basicranial axis 

 of which it is, of course, the anterior part. Posteriorly, 

 liowever — and we shall come to this matter presently, — a 

 ridge arises from the dorsal surface of this rod of cartilage, 

 and is connected (indeed, quite fused) with the meilian rod 

 of the nasal cartilages. It is interesting to note that 



