258 Evolution and Distribution of Fishes 



strata of England, Scotland and Ohio, also in Permian 

 rocks of England. The figures and descriptions given by 

 Pander and by Newberry (z^/ : 41 : PI.57) suggest the 

 appropriateness of such varied generic names as those that 

 Pander employed, no matter what the animals were that 

 carried them. As to abundance, Newberry (p. 41) says 

 that they are "found in great numbers in the Cleveland 

 Shale of the Waverly group at Bedford, Cayuga Co." and 

 that the surfaces of the layers of the shale are sometimes 

 so covered that thousands occur on a square foot, and 

 again, "the number of these objects is immense, and the 

 variety of form which they exhibit is but imperfectly shown 

 in the figures." 



A comparison is made in Figure 7 (p. 108) of some 

 conodont and existing cyclostomatous teeth. And as to the 

 distribution of the former it may be said that the Hamilton, 

 Genesee, and other rocks in which they occur are in part 

 or largely of freshwater origin, but their occurrence much 

 later in the Mountain Limestone, as recorded by Moore, 

 would indicate that they in time spread seaward, as is 

 later traced for elasmobranch fishes. 



Now if one compare the varied shapes of Conodonts as 

 given by Newberry and Hinde (792:351) with the varied 

 descriptions given in condensed manner by Lonnberg 

 (79^:282-288) as well as the descriptions and figures by 

 authors that he cites, it scarcely seems possible that two sets 

 of structures should vary so exactly in parallel manner in 

 different genera and yet belong to totally different groups of 

 animals. ZIttel considers that the histological structure dif- 

 fers; but, If one compares Fig. i that accompanies Beard's 

 paper on "The Nature of the Teeth of the Marslpobranch 

 Fishes" (79^:727) with Zlttel's figure the resemblance is 

 worth noting. It has also been said that Conodonts are 

 calcareous, and cyclostome teeth purely chltlnous, but this 

 need not be a fundamental objection when changes under- 

 gone during fossllization or progressive evolution are con- 

 sidered. The writer then would decidedly favor the view 

 that conodonts are the buccal teeth of primitive cyclo- 

 stomes, but he would welcome more extensive information 

 and details before final decision. 



