386 



SCIENGE. 



[N. S. Vol. IV. No. 90. 



onward flow of the trap, so that the 

 same phenomena appear both at the top 

 and bottom of the trap sheet. In certain 

 localities the wet mnd of the estuary bot- 

 tom, over which the trap sheet flowed, has 

 risen up into the trap, presenting an ap- 

 pearance very similar to that of true tuff 

 beds. In these cases portions of the mud 

 have been metamorphosed into a quartzite, 

 and portions of the molten material of the 

 trap, chilled by the ascending currents of 

 mud and water, have solidified into a pitch- 

 stone or tachylite. 



Prof. N. H. Winchell reported the dis- 

 covery of fragmental volcanic deposits near 

 Duluth, although no remains of craters had 

 been recognized. It is remarkable that, 

 amid the abundant interbedded igneous 

 rocks of the Lake Superior region, only one 

 find of fragmental volcanic deposits had 

 hitherto been reported. 



Prof. J. Perrin Smith gave a lucid ac- 

 count of the Physiography of California, 

 illustrating it by a photograph of a relief 

 map, which was projected on a screen. In 

 discussing the causes of the present physi- 

 ography, he dwelt especially upon the Ter- 

 tiary and post-Tertiary uplifts and conse- 

 quent erosion. 



A number of interesting papers were pre- 

 sented in the department of Paleontology. 

 Prof. E. W. Claypole's paper on Ancient 

 and Modern Sharks gave an interesting ac- 

 count of the peculiarities of ancient sharks, 

 as revealed by the recent discoveries of Dr. 

 Clark and others in the Cleveland shale of 

 northern Ohio. The remains referred to 

 are remarkably well preserved, and throw 

 much light upon the evolution of the Elas- 

 mobranchs. 



Dr. C. E. Eastman gave a very interest- 

 ing paper on the Dorsal Shields of the 

 Dinichthyids. The median dorsal plate in 

 these fishes bears a keel, which is compara- 

 tively slightly developed in Coccosteus, but 

 attains a greater development in other 



genera of the group, reaching its maximum 

 in Dinichthys and closely related genera, 

 in which it is produced backward far be- 

 yond the margin of the plate. This keel 

 is believed to serve for the attachment of 

 muscles for swimming. Dinichthys livon- 

 icus, from Russia, first described by Pander 

 as a species of Coccosteus, is the smallest 

 and earliest species of Dinichthys, and the 

 one most resembling Coccocteus. A com- 

 parison of the different species of Dinich- 

 thys shows that, as the genus moved west- 

 ward from its starting point in eastern Eu- 

 rope, the species increased in size and in 

 difierentiation. 



Mr. F. K. Mixer gave an account of re- 

 cent discoveries of fossil fishes in the Ham- 

 ilton and Portage formations of western 

 New York. The discoveries indicate in 

 the Portage of that region an abundant 

 and varied fish fauna, including groups 

 so diverse as those represented by Dinich- 

 thys, Holoptychius and Palseoniscus. 



Mr. A. "W". Grabau gave a detailed ac- 

 count of the succession of fossil faunas in 

 the Hamilton group at Eighteen Mile Creek, 

 near Bufialo. The comparison of the suc- 

 cession of faunas at Eighteen Mile Creek 

 with that shown in the salt shaft at Livonia 

 reveals a very interesting instance of migra- 

 tion, since the shale beneath the Encrinal 

 Limestone at Eighteen Mile Creek contains 

 essentially the same fauna found in a shale 

 above the Encrinal Limestone at Livonia. 



Prof. A. HoUick gave an account of the 

 exposure of Cretaceous clay marl at Clifi"- 

 wood, ]^. J. The fossils from this locality 

 are poorly preserved, but are of great inter- 

 est as marking a transition from the estua- 

 rine conditions of the Amboy clays to the 

 marine conditions of the overlying marls. 

 The deposit is considered to represent the 

 Mattawan formation of Prof. W. B. Clark. 



Prof. T, H. McBride exhibited micro- 

 scopic sections of remains of Sigillarids and 

 Conifers from the Carboniferous of Iowa. 



