622 REPORT— 1902. 



recently been found the bones of a huge cetacean associated, as in South America, 

 with those of a giant snake, one of the longest known, since it must have 

 reached a length of thirty feet.-^ There also occur the remains of other snakes, 

 of chelonians of remarkable adaptive type, of crocodilians, fishes, and other 

 animals. Interest, however, is greatest concerning the Mammalia, which for 

 novelty are quite up to the American standard, as with an upper and a lower 

 jaw of an anomalous creature, concerning which we can only at present remark 

 that it may be a marsupial, or more probably a carnivore, which has taken on the 

 rodent type in a manner peculiarly its own."** Important beyond this, however, 

 are a series of Eocene forms which more than fill a long-standing gap, viz., that 

 of the ancestors of the Elephants and Mastodons, which hitherto stopped short in 

 the Middle ^Miocene of both old and new worlds. As represented by the genus 

 McBritherium, they have three incisors above and two below, of which the second 

 is in each case converted into a short but massive tusk. An upper canine is 

 present, and in both upper and lower jaws a series of six cheek-teeth, distinct and 

 bunodont in type.-^ In the allied Barytheriuin, of which a large part of the skeleton 

 is known, the upper incisors were presumably reduced to two, the tusks enlarged, 

 with resemblances in detail to the Dinoceratan type.^'' 



So far as these remains are known, they appear to present in their combined 

 characters all that the most ardent evolutionist could desire. There are with 

 them Mastodons which simplify our knowledge of this group ; and among the last 

 discovered remains Sirenians, which, in presenting a certain similarity to the 

 afore-named Mseritherium, strengthen the belief in the proboscidian relationships 

 of these aquatic forms. ^^ Finally, and perhaps most noticeable of all, there is 

 the genus Arsinoitherium, a heavy brute with an olfactory vacuity which 

 outrivals that of Gri/potkeriuni itself, and is surmounted by a monstrous fronto- 

 nasal horn, swollen and bifid, for which the most formidable among the Titano- 

 theres might yearn in vain. There is an occiput to match! The suggestion that 

 this extraordinary beast has relationships with the Rhinoceridse is absurd, since 

 its tooth pattern alone inverts the order of this type. That it is proboscidian 

 may be nearer the mark, and if so it shows once more how subtle were the 

 mammals of the past.-"'- Great as is this result, much remains to be done or done 

 again, if only from the fact that in seeking to determine homologies our American 

 brethren, in the opinion of some of us, have placed too much reliance on a so-called 

 tritubercular theory of tooth genesis, of which we cannot admit the proof.^^ How, 

 we would ask, is it conceivable that a transversely ridged molar of the Diprotodon 

 type can be of tritubercular origin ? 



Sufficient for the moment of palseontological advance, except to remark that 

 the zoologist who neglects this branch of morphology misses the one leavening 

 influence ; neglects the court on whose ruling arguments deduced from embryo- 

 logical data alone must either stand or fall. We may form our own conclusions 

 from facts of the order before us ; but it is when we find their influence on the 

 master-mind prompting to action, like that of Huxley with his mighty memoir of 

 1880, in which he revised our sub-class terms, that we appreciate them to the full.'* 



With this consideration we pass to the living forms, and I have only time 

 in dealing with these to comment on advance which aifects our broadest con- 

 ceptions and classifications of the past. 



To commence with the Mammalia, we now know that the mammary gland 

 when first it appears is in all forms tubular, and that this type is no longer 

 distinctive of the Monotremata alone.^^ We know, too, that the intranarial position 

 of the epiglottis when at rest, long known for certain forms, is a distinction of the 

 class. It explains the presence of the velum palatinum, by its association with 

 the glottis for the restriction of the respiratory passage, the connection being 

 lost in man alone, under specialisation of the organ of the voice. ^'' 



Similarly, the doubly ossified condition of the coracoid may now be held 

 diagnostic, for it is known that the epicoracoidal element, originally thought to 

 characterise the monotremes alone, is always present, and that reduction to 

 a varying degree characterises the metacoracoid, which retires, as in man, as the 

 so-called coracoid epiphysis." 



