394 MR. W.H. FLOWER ON THE SKELETONS OF WHALES [Nov. 8, 
by the union of the second and third, or the third and fourth, by their 
arches. Neural arches high; spines moderately developed. Trans- 
verse process of atlas arising from the middle of the body, elongated, 
tapering, directed outwards, and slightly upwards. Upper and lower 
transverse processes of axis and succeeding vertebree, to the sixth in- 
clusive, well developed. Those of the axis broad, flat, and in the 
adult united at their extremity ; those of the other vertebree slender, 
and never united at their extremity, except occasionally in the sixth 
and more rarely in the fifth vertebra. Head of the first rib simple ; 
capitular processes scarcely developed upon any of the ribs. Sternum 
longer than broad, having the form of an elongated cross (fig. 9). 
Type species, B. rostrata (Fabricius). 
All the Fin-Whales which I have had an opportunity of examin- 
ing fall under one or the other of these groups. There may possibly 
be others, which will need either a new genus to be formed for their 
reception, or a modification of some of the differential characters 
given above. The number of species in the genera Physalus and 
Sibbaldius is at present very uncertain. In Balenoptera, as far as 
is known, there is but one— B. rostrata, Fab.=Pterobalena minor, 
Eschricht and Van Beneden*, 
It may perhaps be useful to place the arrangement of the Bale- 
noidea in a tabular form, so as to show the relation of the different 
divisions to one another (see opposite page). The table also exhi- 
bits at a glance the progressive steps in the classification of the 
group made since the time of Linnzeus, by Lacéptde, Eschricht, and 
Gray respectively. 
I will next proceed to notice in systematic order the specimens of 
skeletons and skulls of Whalebone Whales contained in the Royal 
Museum at Leyden. 
Balena mysticetus (the Greenland Right Whale).—This species 
is represented only by the skull of a very young individual in rather an 
imperfect condition. It is 5! 2" in length, and 2' 103" in greatest 
breadth across the squamosals. The elements of the occipital bone 
are distinct ; but the parietal is already ankylosed with the supra- 
occipital along the upper margin of the temporal fossa. The basi- 
sphenoid is distinct from both the presphenoid and basioccipital, 
though the union with the latter is the more advanced of the two. 
At this stage the skull differs much from that of the adult animal. 
Besides the proportionately greater size of the cranial cavity, the or- 
bital processes of the frontals are shorter, and broader at their extre- 
mity, the maxillaries are less arched, and the skull generally much 
more depressed. 
The Southern Right Whale (Zubalena australis ?).—Of this spe- 
cies, or perhaps I should say of one of the species confounded toge- 
ther under this name, the collection contains a very fine skull of an 
* Barkow (Das Leben der Walle, &c., Breslau, 1841) has described another 
species under the name of Prerobalena pentadactyla; but much uncertainty hangs 
over the origin and composition of the single skeleton in the Museum at Breslau, 
on which it is founded. If genuine, it would necessitate a considerable modi- 
fication of both the family and generic characters. 
