VEETEBRATES. 255 



whereas in Gareharop&is the lateral cones are more numerous, smaller 

 and isolated, and the lateral margins of the median cusp are deeply 

 creuulated in the same manner as in some of the earlier and modern 

 Squaloids. The form described by Dr. Newberry under the name 

 Carcliaropsis Wortlieni, from the Chester limestone of Alabama, (Geol. 

 111. II, p. 69, PI. 4, fig. 14,) is a typical representative of the genus first 

 recognized by Prof. Agassiz and intimately allied to, though probably 

 specifically distinct from, Pristicladodus dentatus of McCoy. Whether 

 or no the latter form is identical with the original species noticed by 

 Agassiz, Carcliaropsis prototypus of the same horizon, we have not been 

 able to ascertain ; but from the comparative reference made by Prof. 

 Agassiz, there can be little doubt as to the generic identity of the two 

 above mentioned forms. 



It will be observed from the preceding diagnosis that the teeth men- 

 tioned herein, and in the following description, are separable into two 

 well-defined groups by not inconspicuous characteristics peculiar to 

 their respective representatives; and in assigning to each of these 

 groups appellations which we believe to have been originally applied to 

 quite different forms, in part at least, by Profs. Agassiz and McCoy, we 

 have been guided by such facts as are accessible to us, only desiring to 

 render due justice to our own authorities. 



Pristicladodus Springeri, St. J. and W. 



PI. I, Fig. 7, 11. 



Under the above designation we refer to a peculiar form of teeth from 

 the Kinderhook formation, which is represented by a unique example 

 in the collection of Mr. Springer, and, although the specimen is in a 

 very satisfactory state of preservation, we have referred it with some 

 doubt to Pristicladodus, together with other specimens which are referred 

 to further on. 



Teeth under medium size, in general outline like Cladodus and in the 

 particulars of form intimately related to Pristicladodus, according to the 

 definition of that genus previously given. Base moderately thick, in 

 outline elliptical, beveled on both surfaces along the broadly rounded 

 posterior margin, outer margin slightly inverted and defined below by a 

 faint marginal ridge, with strong basal protuberances in the angles upon 

 either side of the mesial depression, which latter extends upwards 

 forming a deep triangular area in the base of the median cusp, extremi- 

 ties more or less produced beyond the coronal portion, lateral angles 

 truncated, rounded behind, inferior surface gently excavated and occu- 

 pied transversely to the long diameter by a low median fold, which, 



