498 



SCIENCE. 



[N. S. Vol. n. No. 42. 



Aetosaurus. The Dinosaurs were found at 

 the base of the Jurassic strata. There was 

 no evidence for their existence in the Terti- 

 ary period, but much against it. Owing to 

 their appearance in the Wealden strata, if 

 the evidence derived from Vertebrates is to 

 be regarded as conclusive, the Wealden must 

 be considered as belonging, not to the Cre- 

 taceous, but to the Jurassic formation." 



Professor E. W. Claj'pole's paper on ' The 

 Cladodonts of the Upper Devonian of 

 Ohio ' was as follows: Numerous specimens 

 of the Cladodonts of the Cleveland Shale in 

 Ohio have been found by Dr. Wm. Clark. 

 They for the first time reveal to us the gen- 

 eral form of the fishes to which belonged 

 the teeth that have alone so long repre- 

 sented the genus Cladodus. The fossils are 

 in very fair preservation, but their state of 

 pj'ritization has obscured many of the de- 

 tails of their structure. 80 far as regards 

 their form, however, we now know that 

 they were long, slender fishes, resembling 

 in their character the sharks of the present 

 day; that they possessed well- developed 

 and powerful pectoral and caudal, with 

 weak ventral fins, the dorsals being un- 

 known; that they were for the most part, 

 or altogether, spineless; that at least one 

 species possessed cladodont teeth of more 

 than one pattern; and that they had near 

 the hind end of the bodj' a peculiar flat ex- 

 pansion or membrane of rudely semicircular 

 form, which gave to the caudal extremity 

 when seen from above the outline of a 

 sharp-pointed shovel. 



The largest whole specimen j'et found 

 shows a fish of about 6 feet in length, but 

 detached teeth and other fragments indicate 

 others of double this size, and supply abun- 

 dant proof that in late Devonian times, and 

 in the North American area, the elasmo- 

 branch fishes had attained very great pro- 

 portions and a high stage of development. 



Hitherto the Cladodonts have been re- 

 garded as, in the main, characterizing the 



Lower Carboniferous rocks, but we now 

 find them abounding in the earlier De- 

 vonian strata, and, as shown by the con- 

 tents of their stomachs, preying, in some 

 cases at least, on the smaller placoderms of 

 the same area. 



From the evidence of the new specimens 

 it appears most likely that the species al- 

 ready defined from single and isolated 

 teeth can no longer be maintained. 



For details see the j)apers in the Ajneri- 

 can Geologist for 1S93-4-5. 



Professor Claj-pole also read a second pa- 

 per, illustrated with specimens on ' The 

 Great Devonian Placoderms of Ohio.' The 

 Upper Devonian Shales of Ohio have re- 

 cently afforded a remarkable series of fossil 

 fishes rivalling in size and interest those 

 found many years ago in the Old Red Sand- 

 stones of similer age, in Scotland, and de- 

 scribed by Agassiz and Hugh Miller. The 

 earliest of these, Dinichthys, was closely 

 studied, and its structure was well explained 

 by the late Dr. Newberrj^ It was an im- 

 mense armor-clad fish whose head measured 

 from 2 to 3 feet in length. Titanichthys, the 

 second of the group, though less massive, 

 was of yet larger size. Gorgonichthys, the 

 third, was described by the speaker in 1893, 

 and, so far as is yet known, was the most 

 formidable of all, possessing jaws of enor- 

 mous size and thickness, above 24 inches 

 long, ending in teeth or points from 6 to 9 

 inches in length. The last of the four, 

 Brontichthys, of which a description was also 

 published in the American Geologist for 

 1S94, is equally heavy and of equal size, but 

 differs from all the rest in possessing very 

 massive symphj'sial portions in the mandi- 

 bles with sockets apparentlj^ for the recep- 

 tion of teeth, as in Titanichthys. 



Of the two last-named genera onlj' the 

 jaws are j'et known with exactness. Other 

 portions have been found of Gorgonichthys, 

 but are still imbedded in the matrix. So 

 far as can at present be determined, all the 



