Cope.] 1^2 [May 15. 



exposure, we shall obtain three positives, each showing but one-third 

 of the original negative, and at the same time representing a ditfereut 

 color sensation. An ordinary half-tone plate is now made from each 

 positive, in the usual manner, and then printed successively in yellow, 

 red and blue inks, the same as in the ordinary chromo-typographic or 

 three-color process. 



In the case under consideration you will note the almost perfect 

 result, without the presence of the objectionable mathematical cross- 

 line hatch-work. 



This latter adaptation of the Joly process, I am informed, is the inven- 

 tion of two j'oung men in this country ; and should it prove practical 

 and give certain results, it will without doubt be a great step forward 

 in chromo-tjqjography, and also have commercial value. 



It is a curious fact that the foundations of the interesting processes I 

 have described are based, and depend for their ultimate success, upon 

 the ruling machine — an invention of Joseph Saxton. a former member 

 of this Society, specimens of whose early photo-mechanical reproduc- 

 tions, made in 1841, are still in our possession. 



In conclusion, I will state that the one great advantage which this 

 process seems to ofter over other schemes in heliocliromy or the three- 

 color process, is the fact that but a single negative is required, which is 

 obtained by the ordinary' methods of photography, so tbat all special or 

 intricate apparatus, with uncertain results, are obviated. It will be 

 further noted that the specimens shown here to-night are among the 

 earliest ones made, with crude appliances as to the ruling of the screens 

 and the pigments. 



Second C'ontrihiition to the History of the Cotylosaitria.* 

 By E. D. Co2)e. 



(Read before the American Philosophical Society, 3/ay 15, ISOG.) 



The examination of new material derived from tlie Permian tormatKui 

 of Texas enables me to make some important additions to the knowledge 

 of the Cotylosaurian Reptilia, as set forth in my synopsis i)ublis]R'd in 

 these Proceedings for November, 1895 (p. 437). 



In the first place, I have to describe a type new to the oidcr. and wiiirh 

 resembles nothing hitlicrto found in \\\v Peiiuiaii brds of Xorlh America, 

 or apparently elsewhere. It must be referred to a new Ihniiiy with the 

 fcdlowiiig name and eliaraeters. 



* Read bofore the V. S. National Academy of Scioaces April. ISiH!. 



