No\Ti:MBEK 2, 1906.] 



SCIENCE. 



565 



writers, and in the vast majority of cases the 

 first species is taken by > them as the type. 

 In nearly every case where the A. O. U. 

 Check List and the British Museum Cata- 

 logue differ in the selection of a type species 

 for an ornithological genus, the adoption of 

 the first species by the Americans will bring 

 thera into accord. 



(c) That we have in the 'first species rule' 

 a method that can lead to but one result and 

 can be practised by any one, and by which 

 the type of a genus can be ascertained at once 

 by consulting one reference, instead of in- 

 volving the examination of many works and 

 the expenditure of much time and thought. 



Wither Stone. 



Academy of Natural Sciences, 

 PhiiajDelphia. 



generic names of merycoidodonts. 

 As there has been no recent thorough revi- 

 sion of the Merycoidodonis (Oreodonts auc- 

 torum), based upon an examination and com- 

 parison of all the types, there has been much 

 confusion and error in the use of nearly all 

 of the generic names. Many new forms have 

 recently been discovered, and investigation 

 has been greatly retarded by uncertainty as 

 to where many of these should be placed. 

 By the kindness of those who are in charge 

 of the various museums which contain the 

 types of the genera, the writer has had the 

 opportunity of examining all of the older 

 types, and he here gives his conclusions con- 

 cerning the various names which have been 

 used. 



Merycoidodon Leidy, 

 Type Merycoidodon culhertsoni Leidy. Pro- 

 ceedings Academy Natural Sciences, Phila- 

 delphia, Vol. IV., 1848, p. 47, Plate. 

 Synonyms : Oreodon culhertsoni (Leidy), 0. 

 priscum Leidy, Cotylops speciosa Leidy. 

 The type is a portion of the upper jaw with 

 the, last two molars, and a fragment of the 

 mandible with all the lower molars. The 

 outer cusps of the second upper molar, and 

 the heel of the last lower molar are gone. 

 The t5rpe was sent from the Bad Lands of 

 Dakota by Mr. T. Culbertson and is now the 

 property of the Academy of Natural Sciences 



in Philadelphia. The two specimens probably 

 belong to the same individual, as the last 

 molar in both jaws is in about the same stage 

 of eruption. These molars, though fully 

 formed, had not yet attained the level of the 

 other teeth, but they are well exposed, so that 

 their structure can be easily seen. 



Dr. O. P. Hay (Science, Vol. IX., April 21, 

 1899, p. 593, and 'Catalogue of the Fossil 

 Vertebrates of North America,' p. 665) has 

 reinstated the original name Merycoidodon in 

 the place of Oreodon, which had come into 

 universal use. He says that Merycoidodon 

 clearly has priority over both Oreodon and 

 Cotylops. There is a close similarity in the 

 teeth of the Middle Oligocene Merycoido- 

 donts, and it seemed best, at least until the' 

 type should be found and its identity with 

 ' Oreodon ' demonstrated, to use the commonly 

 accepted name; but now, after having exam- 

 ined the type and compared it with various 

 specimens of so-called Oreodon culhertsoni, I 

 believe that the original name should be used 

 for the following reasons: 



1. The type specimen was fully described 

 by Leidy and figures were published, which, 

 though not clear enough, perhaps, to distin- 

 guish Merycoidodon from specimens of closely 

 allied genera, leave no doubt as to the identity 

 of the type specimen. 



2. The name Cotylops was given to a young 

 individual with the milk dentition. The type 

 of Oreodon was the ' greater portion of a 

 cranium ' with teeth in a very much mutilated 

 condition, sent to Dr. Leidy by Dr. Hiram 

 Prout, of St. Louis. (Proceedings Academy 

 Natural Sciences of Philadelphia, Vol. V., p. 

 237.) 



3. This type appears to be lost, but Dr. 

 Leidy, who was a careful observer, had the 

 types of Merycoidodon, Oreodon and Coty- 

 lops all before him and he said that the true 

 molars of Oreodon had exactly the same form 

 and very nearly the same size as the posterior 

 two molars of Merycoidodon. He afterwards 

 concluded that these genera belonged to the 

 same species. 



4. So far as the present writer has observed 

 there are differences, though not great, which 

 separate Merycoidodon from nearly related 



