1883.] NATURAL SCIENCES OP PHILADELPHIA. 99 



Iguanodontidse, which belong to the Orthopoda^ and the Megalo- 

 sauridse, which pertains to the Goniopoda. To the former, I 

 added the family Hadrosauridae in 1869, and in 1877 T defined 

 the Caniarasauridae , of the suborder Opidhocoela.^ To this family 

 Marsh gave, in 1882, the name of Atlantosauridse? At the same 

 time he proposed a number of families, some of which will be 

 retained, while others are not sufficiently defined. 



The Hadrosauridae are, so far as known, confined to the upper 

 cretaceous beds of North America, and continued, with their 

 accompanying carnivorous genera, later in geological time than 

 any other Dinosauria. Besides the genus Hadrosaurus, I have 

 added the genera Diclonius and Cionodon, and it is possible that 

 the genera Monoclonius, Dysganus and Agathaumas also belong 

 to it. These types are all found in the Laramie formation, 

 excepting Hadrosaurus, which is as jet only known from the 

 older Fox Hills or Maestrichtian, and Pierre epochs. From the 

 latter formations, came also Hypsibema, possibly a member of the 

 same family. 



As the latest in time, the Dinosauria of the Laramie possess an 

 especial interest. Having recently obtained a specimen of a species 

 of the genus Diclonius Cope, I am in a position to give not only the 

 characters of the family and suborder more definitely than here- 

 tofore, but also to furnish some cranial characters of the order, 

 which have been hitherto little known or unknown. The species 

 on which these observations are made is the Diclonius mi?'abilis^^ 

 of Leidy. It is represented by a nearly complete skeleton, in- 

 cluding the skull, which was discovered by Messrs. Wortman and 

 Hill in the Laramie beds of Dakota. At present, I only describe 

 the general characters, and those chiefly cranial, leaving the com- 

 plete description and iconography for my forthcoming volume on 

 the Laramie vertebrate fauna. 



The character which distinguishes this genus from Hadrosaurus 

 is the attenuation of the astragalocalcaneum, and its coossification 

 witi^li the tibia. Ornithotarsus differs from Diclonius in the pro- 



' Proceedings American Philosophical Soc, 1877, p. 243. 



■■^ Araer. Jour. Sci. Arts, 1883, p. 83. 



^ This species is part of the one called by Leidy Trachodon mirabilis, 

 who included in it a species oi Dysganus. He did not characterize the 

 genus Trachodon, and afterwards abandoned it. (Pi-oceedings Academy, 

 Phila., 1868, p. 199.) 



