September 16, 1898.] 



SCIENCE. 



359 



the question with Huxley in 1876 and with 

 Balfour in 1881, and to subsequent progress 

 due to paleontological discoveries. But in 

 spite of these the great gulf between the 

 mammals and reptiles is still unbridged, 

 and he could not agree with Professor 

 Seeley as to the complete collapse of the 

 distinctions. Four points still remained. 

 Great stress had been laid on the affinities 

 between mammals and anomodonts, as 

 shown by the diiFerentiation of the teeth in 

 the latter into three types ; but other rep- 

 tiles, which no one would regard as allies 

 of the mammals, have the same specializa- 

 tion of the teeth, such as the Patagonian 

 crocodile, Motosuchus, and the dinosaur, 

 Ceratopsia. Again, there was no known 

 reptile with two occipital condyles, as in the 

 batrachians and the mammals. Reptiles 

 had been described with double condyles, 

 but he had examined the specimens in ques- 

 tion, and the condyle in each case was really 

 single and only cordate in shape. Thirdly, 

 the absorption of the quadrate bone in the 

 squamosal was not conclusive, as it oc- 

 curred among plesiosaurs and dinosaurs as 

 well as anomodonts, and in each case the 

 quadrate bone was still in existence. 

 Finally, in reptiles the lower jaw consists 

 of several bones and in mammals of but 

 one. He had examined the most mam- 

 malian of the reptiles, and the sutures be- 

 tween the bones were still apparent. The 

 determination of certain bones as pre- 

 frontal he thought should be received with 

 caution. He did not expect that the an- 

 cestor of the mammals would be found 

 among the huge anomodonts, but among 

 smaller animals. 



Professor Haeckel said that he had dis- 

 cussed the problem with Huxley and Lyell 

 32 years before, and the former then 

 strongly held the polyphyletic origin of the 

 placental mammals, the carnivorous and 

 herbivorous groups having descended re- 

 spectively from carnivorous and herbivor- 



ous marsupials. This view was now un' 

 tenable, and the speaker believed that the 

 different series of placental mammals con- 

 verge so nearly that they must all have 

 been derived from one marsupial ancestor. 

 Mr. Sedgwick said that embryological evi- 

 dence had been referred to, but he thought 

 it would help very little. For example, 

 there could be no doubt that the ancestors 

 of horses had many toes, those of snakes had 

 limbs, and those of birds had teeth ; but no 

 trace of these conditions had been detected 

 by embryology. If no light was thrown on 

 such simple problems as these they had no 

 right to expect any on more remote ques- 

 tions. Reference had been made to Pro • 

 fessor Hubrecht's use of the characters of 

 the mammalian ovum. The speaker said 

 it must not be forgotten that in the one 

 genus, Peripatus, the eggs vary more than 

 they do in the whole of the mammals. He 

 expected little help from paleontology, as 

 the ancestors of nearly all existing groups 

 lived in the pre-Cambrian period, and all 

 traces of them had been lost. Professor 

 Hubrecht, in closing the discussion, said, 

 in reply to Mr. Sedgwick, that the value of 

 embryology was destructive, not construc- 

 tive. Its evidence was of value as pro- 

 hibiting certain lines of speculation. He 

 differed from his great teacher. Professor 

 Haeckel, whose present views he thought 

 untenable, since Hill and Semon had shown 

 that in two genera of Australian marsupials 

 have traces of a placenta been found, which 

 in one case is deciduous. He predicted 

 that one great battlefield in the future of 

 this controversj' would be over the question 

 whether mammals had descended from 

 oviparous ancestors. 



Many important contributions were pre- 

 sented before the sectional meetings of the 

 Congress, including papers by Professor 

 Haeckel, Professor Milne - Edwards, M. 

 Dubois, Professor Hubrecht, Professor 

 Marsh, Professor Osborn and other leading 



