^^^ NOTES AND COMMENTS. 489 



The Evolution of the Mammalia. 



Comparative Anatomy, however, when tempered with the results 

 of Embryology and Palaeontology, cannot be misleading to any great 

 extent ; and, notwithstanding Mr. Bateson's conclusions, Naturalists 

 will still retain confidence in such researches as those of the Professor 

 of Phylogeny at Jena, to whose discoveries in the evolution of the 

 Mammalia we have often alluded. Dr. Kiikenthal has just issued 

 {Biol. Centralblatt, vol. xii., pp. 400-413, 1892) another of his striking 

 addresses, which, though partly based upon published papers, con- 

 tains much that is well-expressed and novel. The dentition, as 

 usual, is mainly employed to determine the stage of evolution ; and 

 it is pointed out that in the three groups of Theromorous Reptilia, 

 Marsupials, and Placental Mammals, the teeth become independently 

 specialised in the same directions. In conclusion, the Professor 

 believes that none of the known mammals can have been directly 

 descended from any of the known Theromorous reptiles ; he con- 

 siders, on the other hand, that the ancestors of both these groups 

 must be sought in the Palaeozoic period. 



Such a conclusion is interesting and perhaps justified, but at any 

 rate it is provoking. The " ancestors " of certain well-marked groups 

 of animals recede further and further into remote antiquity, just in 

 proportion to the amount of research devoted to them. The reputed 

 "ancestors" of one author become the "parallel line " of the next ; 

 and the geologist, who is supposed to unearth the desired pedigree, 

 begins to despair of following a kind of will-o'-the-wisp. We cannot 

 help thinking that someday a serious misapprehension will be dis- 

 covered in the prevailing ideas of animal pedigrees. The "imperfection 

 of the geological record " has its limits, and will not account for 

 everything. 



The Evolution of Man. 



However unsuccessful the geologist may have been in unearthing 

 the very earliest mammals, he has certainly done well in discovering 

 the successive stages through which many groups have recently 

 passed ; and these processes of evolution have operated so rapidly in 

 such modern times, that it is difficult to believe they have now en- 

 tirely ceased. In many cases it is difficult to trace the directions in 

 which they are advancing, on account of the paucity of material 

 examined ; but in the case of man, the innumerable variations in 

 anatomy that are constantly being recorded afford a mass of very 

 tangible evidence. 



This evidence has lately been collected by Professor H. F. Osborn 

 in the Cartwright Lectures for 1892, delivered before the Alumni of 

 the College of Physicians and Surgeons of New York, and now printed 

 in the American Naturalist, commencing June, 1892. It is certainly 

 very striking when treated in Professor Osborn's philosophical 



