194 Bibliographical Notices. 
little in the lumbar region before declining again so as to disappear 
in the tail. Just as the elevation of the spine is less remarkable 
than in the former species, so it dwindles away more gradually, being 
very small between the eighth and fourteenth caudal vertebree. The 
differences from the Balenoptera intermedia are rather less striking, 
but are exhibited in the relative size of the centrum, the length of 
the transverse process and the form of the neutral spine in the 
caudal region, which is broad at its upper termination in the Balw- 
noptera patachonica, and narrow or rounded above in the Baleno- 
ptera intermedia. But in the type described in 1865 this difference 
is much less marked. 
The ribs increase in length from 92 centim. in the first to 
1:5 centim. in the fifth; they then diminish to 120 centim, in 
the fifteenth, while the sixteenth is 85 centim. long. On one side 
there is a seventeenth rib 42 centim.long. The differences in form 
of the head of the rib are considerable when the specimen now de- 
scribed is compared with that figured in Proc. Zool. Soc. 1865. The 
sternum is of a broad ‘T-shaped form, having the transverse 
limbs broad and strong, with a longitudinally oval perforation be- 
tween them; the facets for the first pair of ribs are placed close 
behind the great transverse bar. The width of the bone is 45 centim., 
and its length 38 centim. In the remainder of the skeleton the 
divergences from the northern species are less marked. The diffe- 
rences between the scapule of the two individuals are not very 
great in size. ‘The fore limb has a length of 1-80 metre. The pro- 
portions of the several elements necessarily offer but few differences ; 
the radius and ulna are conspicuous for their straightness, and the 
moderate elongation of the olecranon process, which scarcely extends 
beyond the stout humerus. The phalanges are comparatively uniform 
in character: the middle digit, as usual, is the longest; it contains 
seven phalanges, while there are six in the fourth, and five in the 
fifth digit. There is no trace of a hind limb, except a triangular 
bone, which is probably to be referred to the pelvis. 
Having described the skeleton, the author discusses the characters 
on which he relies to distinguish it from Balenoptera musculus. In 
the head specific characters are found in the relative width of the 
parietal, frontal, and the orbital plate of the maxillary, Another 
difference is in the intermaxillary being stronger posteriorly ; and it 
encloses a long elliptical hole above the vomer, while in the southern 
species this hole is short. The occipital bone is broader in the 
southern form. There is apparently one more dorsal vertebra and 
at least one more pair of ribs. 
Balenoptera intermedia is known from both male and female 
specimens. It is intermediate between the Balenoptera patacho- 
nica and the Balenoptera Sibbaldii. The body of one specimen was 
58 feet long ; where thickest, behind the pectoral fin, it was about 
9 feet high. The lower jaw extended somewhat in advance of the 
head. ‘he pectoral fin has a sickle-shaped form, is 8 feet long and 
3 feet wide in the broadest part, and is placed 5 feet behind the eye. 
The whole of the underside is marked in its anterior half with parallel 
