202 
DES. A. CAETE AND A. MACALISTEE ON THE 
being 15' 10". The proportion existing between these two measurements in the present 
specimen was as 9 to 18f, which will be seen to approximate closely to the proportionate 
measurements of Knox’s specimen, in which the girth was to the length as 9 to 17 ; 
and it differed but little from the same relative dimensions of the foetus described by 
Eschricht, which he states was 1' 6f" in circumference and 3' in length ; while, on the 
other hand, it differed considerably in these proportional measurements from the speci- 
men described by Hunter, in which the girth of the animal was less than a third of its 
length 
External Form. 
From the central line of its greatest circumference, which was about 2 feet behind the 
posterior border of the anterior extremity or paddle, the body gradually tapered forwards 
to the level of the posterior canthus of the eyelids, from whence it narrowed much 
more rapidly to the anterior extremity of the snout, without any indication of the frontal 
convexity which has been represented on the forehead of a foetus of this species by 
Eschricht, and figured in the first volume of the ‘ Untersuchungen fiber die Nordischen 
Wallthiere,’ Tab. VI. fig. 1. 
The outline of the head was much more pointed in front, when seen in profile, 
than when viewed from the dorsal aspect ; the difference being due to the great lateral 
width of the interval between the rami of the lower jaw at their point of greatest 
convexity, which caused the transverse diameter of this portion of the head to be 
greater than the vertical. The contour lines of these aspects likewise differed, as 
when viewed from above they were curved, whereas when seen on its lateral aspect 
the head appeared more decidedly wedge-shaped with straighter borders. The point 
of greatest lateral convexity in the inferior maxillae was situated about 21 inches behind 
the symphysis. 
Posterior to the before-mentioned point of greatest width the body commenced to 
taper backwards, and as it merged into the tail was altered from its cylindrical form, 
and became in section somewhat lozenge-shaped, with its major axis directed from the 
dorsal to the ventral surface. 
This alteration in the figure of the body at its caudal extremity was due to the 
presence of a slight dorsal and ventral ridge, the former of which was continued from 
behind the posterior edge of the dorsal fin, and extended down to the notch that sepa- 
rated the lobes of the tail; this ridge at its origin was rather obscure, but as it 
approached the tail became somewhat more distinct. 
As in all the species of Balcenojptera and its allied genera, a dorsal protuberance or 
fin existed, which in outline was the shape of a scalene triangle, its apex being directed 
backwards, its anterior edge convex, and its posterior falcate. 
Hunter conjectured the use of this appendage to be to prevent the animal rotating in 
the water*. 
* But little value is to be attached most probably to tbe precise position of the dorsal fin, as a means of dis- 
tinguishing species, as from the descriptions of the different individuals recorded it would appear to vary con- 
siderably. Dr. Gkay states that it is placed about two-thirds of the length of the entire body from the point 
