Hatcher : Litti,f. Known Fossil Vertebrates. 129 



locality that afforded Marsh's types, and was fortunate in finding a 

 third fragment (No. 104)' of a dental plate with two teeth in position 

 and exhibiting the scars of several other detached teeth as shown in 

 Plate I, Figs. 5 and 6. These teeth have chisel-shaped crowns and 

 are very much compressed, api)arently with the longer axis directed 

 transversely. They are (piite distinct from other dental plates found 

 somewhat abundantly in the same deposits, which are also of ichthyic 

 nature, but in which the crown of each tooth consists of a single 

 rather low tubercle, circular in cross-section. 



Class REPTILIA. 



Subclass Dinosauria. 



Order PREDENTATA. 



Suborder Ornithopoda. 



The Dermal Covering of Claosaurus ^ Marsh. 



The first information regarding the nature of the dermal covering of 

 dinosaurs was given by the writer in a brief communication to Science 

 on The Carnegie Miiseiiin Paleoulological Expedition of igoo.^ A little 

 later Mr. F. A. Lucas'' called attention to the appearance of dermal 

 impressions similar to those mentioned by the writer, and shown by 

 material collected by Mr. Robert Butler for the U. S. National 

 Museum, and pertaining to the same genus, Claosaunts (Thespesius), 

 as does that on which the present observations are based. Through the 

 kindness of Mr. Lucas I am able to give here (Fig. i) an illustration, 

 natural size, of these impressions as represented on a slab of sandstone 

 enclosing the bones of one of the fore limbs of the specimen in the 

 U. S. National Museum. 



"The numbers enclosed in brackets in this paper refer to the Card Catalogue of 

 Fossil Vertebrates in the collection of the Carnegie Museum. 



* Claosaurus Marsh has been considered to be a synonym of Thespesius Leidy, 

 (See Lucas, in Science, N. S., Vol. XII, Nov. 23, 1900. p. 809) ; while the latter 

 genus has been considered a synonym of Hadrosaurus Leidy, by another authority. 

 (See Dinosaurierfeste aus Siebenbilrgen, by Franz Baron Nopsca, jun., Band 

 LXVIII der Denkschriften der Mathematisch-Naturwissenschaftlichen Classe der 

 Kaiserlichen Akademie der Wissenschaften, pp. 555-591.) In consideration of the 

 incomplete nature of Leidy' s type of Thespesius I retain Claosaurus. 



5 See Science, N. S., Vol. XII, Nov. 9, 1900, pp. 719-720. 



® See Science, N. S., Vol. XII, p. 809. 

 9 



