140 Anatomy of Sperm Whale. Fetus 
eye. This character has been noted by Schulte in the embryo of a 
rorqual, who points out its ‘‘remote and specious resemblance to that 
of the sauropside embryo.” It is at any rate not without interest to 
find that this character is to be found in two whales so far apart, as 
are Physeter and Balcenoptera, in the scheme of the Cetacea. The 
Plate shows this continuing line in the two youngest embryos, but it 
is not so pronounced as the figures given by Schulte*. | Hentschel? 
has given an elaborate mapping of no less than seven throat grooves 
in the adult Cachalot. Of these, two are especially pronounced, and 
have been described as the only ones by other observers. I have 
already mentioned that I can find no such throat furrows in the older 
feetus reported upon by myself in this Journal. I have carefully 
inspected the two new feetus dealt with in the present communication 
and can find in them no trace of any such grooves. It seems clear, 
therefore, that this character is one of late appearance. 
A final point with reference to the head is the general shape of the 
same when seen from above. I have described and figured that of the 
oldest of the three foetus in my former memoir in this Journal. I have 
now to point out that the ten-inch feetus of the present communication 
shows no differences from the older one. In the smallest fetus, 
however, the head, when seen from above, as is represented in the 
accompanying illustration (fig. 3), is rather different. I have already 
dealt with the nasal prominence to be seen on that aspect and to the 
line of the nasal furrows. There is, furthermore, a great contrast 
between the head generally and the fore-part of the same. It 
suddenly narrows a little way in front of the nasal prominence to form 
what looks like a beak in this aspect. The contours, when seen from 
above, are much like those of a sharp beaked dolphin, and the diameter 
of the beak is only some 4 mm., as contrasted with 10 mm. or so at 
the middle of the head. It is thus a stage lower than the two more 
mature foetus which are themselves intermediate between the smallest 
feetus and the adult whale, where the diminution in breadth of the 
head anteriorly is quite gradual, as shown, for instance, in Hentschel’s 
figure of the same. } 
The upper surface of the head of this small embryo is smooth and 
rounded, suggesting a bird’s head. The older feetus on the other 
hand is much folded longitudinally into a few thick folds (see fig. 6), 
which seem to be responsible for the slope of the head upwards 
* loc. cit., figs. 1, 2. p. 400. 
+ Zool, Anz., Bd. XXXVI, 1910, p. 422, fi 
t Zool. Anz., t. cit., p. 418, fig. 1. 
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