by Frank E. Beddard. 139 
blowhole, so that the alleged rudiment of the right orifice in that 
feetus is without such significance and a mere skin furrow of no 
meaning. On this view there is but one external orifice, divided from 
the very first by a septum. I believe, however, that this is incorrect. 
The right blowhole of the youngest feetus cannot be ignored. In this 
foetus the right blowhole is already smaller on the right side of the 
head (figs. 1, 2) than that of the left side on the left, and it is also in 
the form of a straight line, while the left blowhole is crescentic, the 
concavity being downwards.  Obliterate still further the right hand 
section of the entire area of the formation of the blowholes, leaving the 
median portion attached to the anterior extremity of the left blowhole, 
which would naturally curve to the right and later on upwards, and 
the / shaped left blowhole of the adult is acquired. The median 
septum would then represent the shallow furrow of the youngest foetus 
connecting the two nostrils. But, as already mentioned, I have no 
stages to show that this course has been taken. We might therefore 
regard the apparent right blowhole of the oldest foetus as an 
exceptional remainder; and it will be noted that it is straight in 
direction in contrast with the curved left blowhole. ‘This is what we 
find also in the youngest feetus. 
Lower JAW AND SOME OTHER FEATURES OF THE Heap. 
Another feature characteristic of the smallest foetus, which is, 
however, very transitory, is evident in fig. 1 of Plate XXIII. This 
is the extension of the lower jaw beyond the upper, and the fact that 
it is rather bent down at the free extremity. There is no trace of 
such extension in the next oldest fctus, the lower jaw of which is 
roughly equal in length to the upper jaw. It might appear possible 
to make some comparison of this fact with the conditions obtaining in 
the adult Lerardius, and others of the Ziphiid whales, where the 
prominent lower jaw is figured, for instance, by True*, especially 
when the projecting lower jaw of Megapteray is seen to be plainly 
indicated in the young fetus. I may also remark that in this fetus 
and the older ones the line of the mouth is faintly prolonged by a 
shallow furrow on the skin some way beyond, and of course below, the 
* An Account of the Beaked Whales of the Family Ziphiidz, etc., Smiths. 
Inst. U.S. Nat. Mus., Bull., 78, Pl. 42, fig. 3; and of Ziphius, Pl. 41, fig. 4. 
+ Brit. Mus. (Nat. Hist.), British Antarctic Exped., 1910, Nat. Hist. Rep. 
Zoology, Vol. I, no. 3. Cetacea by D. G. Lillie, Pl. I and Pl. IV, fig. 4. This 
character, however, is hardly or not at all shown in the figures of Kiikenthal 
(loe. cit.), 
