388 MR. W.H. FLOWER ON THE SKELETONS OF WHALES [Nov. 8, 
leton of Physalus antiquorum in the Alexandra Park, prepared by 
Mr. Gerrard, jun.; they measure, the one 193" in length, the other 
27", and taper to a point at their upper extremity, being suspended 
in the position they originally occupied, far removed from the ver- 
tebral column. A small rudimentary additional rib, or pair of ribs, 
attached to the first lumbar vertebre is sometimes developed ; but a 
fully formed pair of ribs above the normal number is, I believe, 
never met with. 
As to the number of vertebrae, a small amount of latitude may 
usually be allowed on account of the difficulties connected with the 
terminal bones of the tail. Very often in specimens in museums 
several of these are wanting, owing to carelessness in preparing the 
skeleton ; and by a less excusable carelessness the circumstance may 
not be noted in published accounts of the number of vertebree pos- 
sessed by the specimen. But even if all are present, slight discre- 
pancies in enumeration readily occur. In early periods of life, the 
last vertebra, although certainly formed in cartilage, is not ossified, 
and the penultimate has so much the appearance afterwards assumed 
by the last, as frequently to be taken for it ; or, again, later in life two 
or even three of the terminal vertebral elements grow together so as 
to form a single osseous mass, which is counted as one or several 
bones according to the discretion of the observer. Therefore, even 
in well-described skeletons, a discrepancy of one or two in the given 
number of caudal vertebrz is of no great consequence; but there is 
no evidence to prove the occurrence of any greater variation in any 
given species. 
It would be interesting to collect an account of the numerous and 
various differences in detail found in the osteological structure of 
several individuals of each well-determined species; but to do this 
with advantage would cause me greatly to exceed the limits originally 
proposed to this paper. I shall have occasion to mention some of 
them hereafter, and will next proceed to give such a sketch of the 
arrangement of the genera of the Whalebone Whales as may explain 
the names assigned to the different specimens mentioned in the fol- 
lowing notes. The materials at our disposal are still so scanty, that 
I do not suppose that the classification now offered may not here- 
after require modification; but it has not been attempted without 
a personal examination and a very careful consideration, at all events, 
of all the more important osteological characters of several individuals 
of each genus. 
I perfectly concur with those naturalists who divide the Cetacea 
into two primary sections, which merit, it appears to me, the rank of 
suborders. The BALaNo1pEa or Mysticete, or Whalebone Whales, 
and the DeLpHiNorpEA or OponToceETE form two natural and equi- 
valent groups, separated from each other by the following (among 
many others of less importance) trenchant distinctions :— 
I. BaLaznorpea. Teeth never functionally developed, but always 
disappearing before the close of intra-uterine life. Upper jaw pro- 
vided with plates of baleen. Sternum composed of a single piece, 
generally broader than long, and counected only with the first rib. 
