226 THE CANADIAN NATURALIST. [June 



Reptiles already described by my predecessors — Leidy, Owen, 

 Dawson, Wyman, Lea, etc. Where, however, I have had 

 nothing to add, I have referred to their published descriptions, 

 which are numerous and well-known. The literature of the 

 subject will then be found under the respective specific heads." 



" In the course of these investigations, prosecuted during the 

 past six years, with reference to the structure and relations of the 

 extinct Reptilia, the following general conclusions have been 

 attained to, besides many of lesser significance. 



First — That the Dinosauria present a graduated series of 

 approximations to the birds, and possess some peculiarities in 

 common with that class, standing between it and the Crocodilia. 



Second — That serpents exist in the Eocene formations of this 

 country. 



Third — That the Chelydra type was greatly developed during 

 the American Cretaceous, and that all the supposed marine 

 turtles described from it are really of the first named group. 



Fourth — That the Reptilia of the American Triassic are of the 

 Belodon type. 



Fifth — The discovery of the characters of the order Pythono- 

 morpha. 



Sixth — The development of the characters of numerous 

 members of the Batrachian Sub-order Microsauria in the United 

 States." 



Marine Crustaceans in Lakes. — Several years ago Prof. 

 Loven discovered in fresh-water lakes in Sweden forms of Crus- 

 tacea previously found only in the sea, and inferred that these 

 species had been left behind in the upheaval of the land, and were 

 thus living witnesses of the great subsidence and re-elevation of the 

 land in the Post-pliocene period. It was, we believe, suggested 

 at the time in this Journal that our Canadian Lakes afi'orded an 

 admirable opportunity to extend these observations ; but in so 

 far as we know this has not been done until last summer, when 

 Dr. Stimpson, by dredging in the deeper parts of Lake Michigan, 

 obtained a species of Mysis closely allied to one of the Swedish 

 species ; thus apparently indicating a former marine condition of 

 the basin of our great lakes. The subject deserves further 

 attention, and would well repay the exertions of any of our 

 Canadian naturalists residing in the vicinity of the lakes, in the 

 deeper parts of which the dredge would no doubt discover many 



