VERTEBRATE ZOOLOGY. 499 



cannot refrain from expressing our doubts whether Professor 

 Marsh will be justified in proposing to distinguish the new- 

 ly found type as an order distinct from the Ichthyopterygia. 

 The mere presence or absence of teeth in the jaws is general- 

 ly, and apparently very properly, regarded as of no very 

 great systematic value, and unless other characters are asso- 

 ciated with the negative or positive character in question, 

 groups so differentiated may be very closely related. Doubt- 

 less, however, the character in this instance, at least, is of 

 family importance ; and we may therefore hail, in the Saura- 

 noclontidce, a type especially interesting in its morphological 

 as well as its creolosfical relations. 



An American Jurassic Mammal. 



As is well known, mammals older than of tertiary age are 

 among the rarest of fossils, and the discovery of a species in 

 this country of Jurassic age is therefore noteworthy. The 

 greater part of the right lower jaw (deprived, however, of all 

 the teeth except the penultimate molar) of a small animal 

 about the size of a weasel was obtained in the beds desisr- 

 nated,by Professor Marsh, as the " Atlantosaurus beds of the 

 Upper Jurassic." This fragment has served for the founda- 

 tion, by Marsh, of the Dryolestes priscus, representative of a 

 new genus as well as species. The tooth preserved, it is 

 said, "has the same general form as the corresponding molar 

 of Chironectes variec/atus, Illiger," the water -opossum of 

 South America. Although doubtless a Marsupial, nothing 

 positive can be predicated from the known remains. It may 

 be remarked as a singular fact that of the now quite numer- 

 ous species of Triassic and Jurassic mammals known, almost 

 nothing but the lower jaws have been found, and, as has 

 been indicated, the Dryolestes is not an exception to the 

 rule. 



The Miocene Mammalian Fauna of Oregon. 



Through the labors of Messrs. Leidy, Marsh, and Bettany, 

 a considerable number of species of mammals of the order 

 of Ungulates have been made known as representatives of 

 the Miocene fauna of Oregon, but of the other types of the 

 class almost nothing was known. Towards the end of last 

 year, however, Professor Cope contributed a memoir "on some 

 of the Characters of the Miocene Fauna of Oregon," which has, 



