that anything can be decided on this subject, which is one of very great difficulty, as well as interest.
The distance of the pectoral fins from the posterior angles of the mouth, might be supposed as varying with the greater or lesser dilata- tion of the folded thoracic membrane; but it is evident that the only effect, if any, produced on the anterior limbs, would be a vertical, and not a horizontal change of position.
I maintain that the colouring of the characteristic folds does not vary with age, and from the same motive stated when speaking of the baleen, that age and size have not the slightest relation with the colouring, which is constant. The red maculation of the up- per lip has never been found on any other species than the ones which I regard as identical with the specimens noticed by myself.
The number of vertebræ is not yet sufficiently well ascertained to allow of its being employed as a good character, but it is exceedingly improbable that this number should be as variable as has generally been supposed, for a skeleton must have been prepared with the ut- most negligence to have lost as many as seventeen vertebrae ; and forty-eight to sixty-three vertebrae, are numbers too different to be supposed to exist in any one species of Mammalia.
I believe I may affirm, that no other placental animal produces young (one in number), which, at their birth, would be as small as those of the Northern Baleinopteræ considered as one species : the measurements of specimens of all sizes, from ten feet to a hundred and twenty, having been recorded in different works.
All the preceding remarks may, without any doubt, be criticised, and most likely will be, but I doubt whether they will be easily re- futed : if they only serve to attract the attention of some naturalist to this interesting subject, I shall deem myself happy to have given rise to new observations, which to be useful must be detailed and correct.
After all, is it not better to adopt a species too many, than to abo- lish one on insufficient grounds ? In the first case, a simple notice of the error, when discovered to be really such, mends the harm for ever ; whilst in the latter case, a fact is entirely lost, and a link is missing in the chain, or a mesh in the great net of the " Natural System."
The characters I have made use of are entirely external ; the inte- rior parts having seldom been described, it is next to impossible to make use of them specifically at present, but I intend on a future oc- casion publishing my observations on this subject.
1 shall now say a few words concerning the animal which induced
