1883.] on Whales, Past and Present, and their Probable Origin. 13 



developed limbs, but so situated that it is almost impossible to 

 conceive that they can be of any use ; the whole limb, such as it is, 

 being buried deep below the surface, where any movement, except of 

 the most limited kind, must be impossible. Indeed, that the move- 

 ment is very limited and of no particular importance to the animal 

 was shown by the fact that in two out of eleven whales dissected the 

 hip-joint was firmly anchylosed (or fixed by bony union) though 

 without any trace of disease. In the words of Dr. Struthers, " Nothing 

 can be imagined more useless to the animal than rudiments of hind- 

 legs entirely buried beneath the skin of a whale, so that one is inclined 

 to suspect that these structures must admit of some other interpreta- 

 tion. Yet, approaching the inquiry with the most sceptical deter- 

 mination, one cannot help being convinced, as the dissection goes on, 

 that these rudiments really are femur and tibia. The functional point 

 of view fails to account for their presence. Altogether they present 

 for contemplation a most interesting instance of those significant 

 parts, rudimentary structures." 



We have here a case in which it is not difficult to answer the 

 question before alluded to, often asked with regard to rudimentary 

 parts, are they disappearing or are they incipient organs ? We can 

 have no hesitation in saying that they are the former. All we know 

 of the origin of limbs shows that they commence as outgrowths upon 

 the surface of the body, and that the first-formed portions are the 

 most distal segments. The limb, as proved by its permanent state in 

 the lowest Vertebrates, and by its embryological condition in higher 

 forms, is at first a mere projection or outward fold of the skin, which, 

 in the course of development, as it becomes of use in moving or 

 supporting the animal, acquires the internal framework which 

 strengthens it and perfects its functions. It would be impossible on 

 any theory of causation yet known, to conceive of a limb gradually 

 developed from within outwards. On the other hand, its disappearance 

 would naturally take place in the opposite direction ; projecting parts 

 which had become useless, being in the way, would, like all the other 

 prominences on the surface of the whales, hair, ears, &c., be removed, 

 while the most internal, offering far less interference with successful 

 carrying on the purposes of life, would be the last to disappear, 

 lingering, as in the case of the Greenland Whale, long enough to 

 reveal their wonderful history to the anatomist who has been fortunate 

 enough to possess the skill and the insight to interpret it. 



Time will not allow of more illustrations drawn from the structure 

 of existing Cetacea ; we turn next to what the researches of palaeon- 

 tology teach of the past history of the order. Unfortunately this does 

 not at present amount to very much. As is the case with nearly all 

 other orders of mammals, we know nothing of their condition, if they 

 existed, in the mesozoic age. Even in the Cretaceous seas, the 

 deposits at the bottom of which are so well adapted to preserve the 

 remains of the creatures which swam in them, not a fragment of any 

 whale or whale-like animal has been found. The earliest Cetaceans 



