September 12, 1S84.] 



SCIENCE. 



261 



thence into streams; while other forms, especially 

 during earlier geological times, owe their transfer 

 into fresh water to the changing of marine into 

 lacustrine areas. Professor Sollas reviewed some of 

 the relations which the origin of certain fresh-water 

 forms have to geological periods and changes, and 

 considered some of the causes of modification of 

 form and of prolongation of embryonic life of marine 

 animals. 



On the succeeding days a few papers upon the geo- 

 graphical distribution of animals were presented. 

 Dr. G. E. Dobson pointed out that many of the most 

 characteristic species of the chiropterous fauna of 

 Australia have their nearest allies not in the Oriental 

 but in the Ethiopian region, and instanced the pres- 

 ence of species of certain genera of bats in Mada- 

 gascar and Australia which were poorly or not at all 

 represented in India. We are therefore obliged, for 

 this and other reasons, to suppose, that, at a com- 

 paratively recent period, a chain of islands connected 

 Madagascar with Australia; the islands being suffi- 

 ciently far apart to prevent the distribution of ter- 

 restrial mammals, yet near enough to permit the 

 occasional passage of flying species. Later, a tem- 

 porary connection of a similar kind probably ex- 

 tended between Madagascar and India. Treating 

 geographical distribution of animals in a less general 

 manner, was a paper by Mr. Howard Saunders on 

 the geographical distribution of the Laridae (the gulls 

 and terns), with special reference to Canadian 

 species. 



As to the distribution of plants, Professor Asa Gray, 

 in his remarks on the characteristic features of North- 

 American vegetation, called attention to the resem- 

 blances and the differences between the flora of North 

 America and that of Europe, and to the causes of 

 these resemblances and differences. The similarity 

 of the trees of the Atlantic border to those of Europe 

 was alluded to, and its cause discussed ; and mention 

 was made of the pleasure which the European botanist 

 would experience in finding, in the new world, plants 

 growing wild which are cultivated in the gardens of 

 Europe. Among these are species of Rhododendron, 

 Cypripedium, and Coreopsis. Turning to the differ- 

 ences between the flora of Europe and America, the 

 wealth of species of trees and shrubs in the latter 

 country was illustrated by numerical comparisons of 

 the species of oaks and of many other trees in Canada 

 with those found in England. Besides the far more 

 numerous kinds of leguminous trees, and the remark- 

 able wealth in species of Compositae which is notice- 

 able in America, there are many tropical plants which 

 extend northward into the United States. Such are 

 various trees, and Sarracenia, Passiflora, Tillandsia, 

 and numerous other herbaceous plants. After dis- 

 cussion of the part which the ice of the glacial period 

 played in the distribution of plants over Europe and 

 North America, Professor Gray reviewed the charac- 

 teristics of the flora of the middle and western por- 

 tions of North America. This paper was one of the 

 few which the general committee voted to print in 

 full in its proceedings. 



Remotely connected as it is with the question of 



the distribution of trees in the United States, atten- 

 tion maybe called to the Jesup collection in the New- 

 York museum of natural history, which was briefly 

 described in a paper by Prof. A. S. Bickmore. This 

 collection, besides illustrating the wood, bark, leaves, 

 and other parts of the trees of the United States, by 

 dried specimens or by figures, inside the museum, is 

 supplemented by having the trees about the museum 

 numbered to correspond with the specimens, so that 

 immediate reference can be made to the museum by 

 any one who wishes to learn more about a tree seen 

 in the park. 



On the question of the affinities of different groups 

 of animals, as shown by their anatomy or develop- 

 ment, several papers of importance were read ; but of 

 the greatest value was the announcement made in a 

 brief telegram from Professor Liversedge, in Aus- 

 tralia, announcing that Mr. W. H. Caldwell, who is 

 in Australia in order to study the development of 

 some of the curious animals found there, had dis- 

 covered that the Monotremata are oviparous, and 

 that the egg is meroblastic. No statement was given 

 in the telegram as to whether the facts were deter- 

 mined as regards Ornithorhynchus or Echidna; but 

 the main points of interest are the discovery of the 

 oviparous habits of a mammal, and the meroblastic 

 development of its egg, as in reptiles, since the eggs 

 of mammals are regularly holoblastic. This shows 

 that we must turn to the reptiles for the ancestors of 

 the mammals. 



Prof. O. C. Marsh read a paper on the classification 

 and affinities of dinosaurian reptiles. It was replete 

 with facts derived from the large amount of material 

 which has been accumulated within the last half- 

 dozen years. Three orders were recognizable in the 

 herbivorous, and one order in the carnivorous dino- 

 saurs. In the carnivorous groups we have forms with 

 greatly enlarged pelvis, and animals that sat down. 

 One of them which was found the past, year, Cerato- 

 saurus, exhibits new characters for a dinosaur. The 

 vertebrae are smooth in front and concave behind. 

 The pelvis is made up of three cocissified bones, as it 

 is in birds, and not of separate bones as in Archae- 

 opteryx and in other dinosaurs. Ceratosaurus also 

 agreed with adult birds in having the three meta- 

 tarsal bones coossified. The dinosaurs are thus shown 

 to be very closely related to birds; and, in answer to 

 a question, Professor Marsh called attention to the 

 correspondence between the double sternum of larger 

 dinosaurs and the ossification of the sternum from 

 two centres in young birds. 



Prof. A. Milnes Marshall showed, in a paper on 

 the mutual relation of the recent groups of echino- 

 derms, that Carpenter was correct in regarding the 

 central capsule with its radiating axial cords in 

 Comatula as the central nervous system, while the 

 subepithelial bands, which Ludwig and others have 

 regarded to be the true nervous system, are, in reality, 

 nervous in character, but of subordinate importance. 

 Professor Marshall has proved these points by a series 

 of conclusive experiments, which he conducted at 

 Naples upon the living animals. In regard to the 

 homologues of the parts of the nervous system of 



