136 Anatomy of Sperm Whale Fotus 
and in his figure it is to be seen that, although the blowhole lies upon 
the left side of the head and is thus asymmetrical, as in the adult 
Physeter, the line of the furrow just crosses over the median line of 
the head, and, furthermore, there is a division in the actual orifice 
between a larger left and a minute right aperture. Both these, 
however, occur in the same continuous furrow and there is no hint of 
two completely separated blowholes. It must be remembered, however, 
that in other toothed whales the single orifice, although originally 
double, are very early fused into a single opening. — It is, therefore, 
perhaps not to be expected that an actual separation of the two halves 
of the blowhole could be found in so comparatively old a foetus as even 
the youngest of those which I have examined. But although there is 
no separation, it seemed to me that the furrow representing the future 
blowhole, admittedly deeper on the left side than in the median region 
of the “nose,” where it was continuous over to the right side, again 
became deeper on the right side. ‘This matter, however, must be left 
until the blowhole in all three foetus have been compared. 
In the intermediate foetus, measuring ten inches or so in length, the 
blowhole is extremely conspicuous and easy to study. It appears 
indeed to have been partly everted since the dorsal and ventral lips 
are quite wide apart. The general direction of the cleft is almost at 
right angles to the longitudinal axis of the head and is much at the 
same angle as in the youngest feetus. On the other hand, in the 
foetus of 20 inches, as I have already described, the left blowhole has 
moved so as to be much more parallel to the long axis of the head. 
The change of position is very marked; and in the oldest feetus it 
has nearly, if not quite, gained the relations which it shows in the 
adult. The form of this slit-like orifice in both these feetus has 
certainly acquired the characteristic / shape of the adult Physeter 
macrocephalus. The proportionate length is more nearly acquired in 
the feetus of 20 inches than in that of 10 inches. In the adult 
Physeter, according to measurements of Hentschel*, the blowhole is 
50 em., while the length of the whale itself is 1,740 cm., the 
proportions being thus 1:35. In the older fcetus at my disposal the 
blowhole measured 15 mm. in a straight line not allowing for the 
curves, giving therefore a proportion of 1:33, while in the smaller 
foetus of ten inches the length of the blowhole was 11 mm., giving the 
proportions of only 1:22. In my already quoted paper upon the older 
foetus IT have given the length of the left blowhole as 17 mm. but this 
allowed (I presume) for the curvature of the same. So much then for 
* Zool. Anz. t. cit. 
