A CLASSIFICATION OF THP: TOOTHLIKE FOSSILS, 

 CONODONTS, WITH DESCPaPTIONS OF AMERICAN 

 DEVONIAN AND MISSISSIPPIAN SPECIES 



By E. O. Ulricii 



Of the United States Geological Survey 



aud 



Ray S. Bassler 



Of the United States National Museum 



A discussion of the systematic position of the conodonts formed 

 the basis of the senior author's first paper published in 1878 ^ At 

 various times since that date, and during the past 20 years in as- 

 sociation with the junior author, lie has made quite extensive col- 

 lections and studies of these difficult toothlike organisms. In his 

 first paper, the senior author accepted somewhat reluctantly the 

 prevailing opinion that the conodonts, like the more unquestionable 

 annelid jaws, were the booklets of species of annelids. In the 

 subsequent comparison the true conodonts were early discriminated 

 from the annelid jaws by him but until the present time no oppor- 

 tunity has been afforded to prepare and publish the results of these 

 studies. The main intention of the present publication is to make 

 these conodonts more available for detailed stratigraphic work by 

 introducing a comprehensive classification. That this classification 

 may be to some extent artificial is recognized. Plowever, after 

 extending our studies to such recent fishes as the Myxines and small 

 selachians in which similar teeth and dermal plates occur, we feel 

 certain the prevalent opinion that many kinds of these teeth may 

 occur in the same mouth, or plates in the same dermal armor, is not 

 warranted by the facts. Except that there are right and left pairs 

 belonging in the case of teeth, to the right and left sides of the upper 

 and lower jaw, the minute teeth wherever located in the mouth of the 

 supposed living relatives of tlie conodonts, are essentially alike and 

 thus each kind is characteristic of some particular genus and species. 

 The dermal ossicles or plates are similarly divisible into right and 

 left pairs but aside from this difference in addition to the easily 



'Journal Cincinnati Society Natural History, vol. 1, 1878, pp. 87-91. 



No. 26I3-— Proceedings U. S. National Museum, Vol. 68, Art. 12. 



60728—26 1 



