Dr. Tf. J. Barkm — Hybodus^ a Coal-measure Fish. 167 



As I have before remarked, all teeth resembling Hybodus were 

 judged to belong to the genus Gladodus if they were found in the 

 Carboniferous strata ; but in any case, whether they are two different 

 genera, or whether they are all Gladodus, their appearance in these 

 Measures is very rare indeed. I have examined during the last few 

 days the collections of three different local palaeontologists, and 

 have been able to discover only sixteen teeth among them, all of 

 which, however, are very well shown, so that their characteristics 

 can be easily detected. Among these sixteen teeth only two present 

 the external form and appearance described by Agassiz as belonging 

 to Gladodus, one being in the possession of my father, the other 

 in the cabinet of Mr. Simm, of Cramlington ; these two teeth I have 

 exhibited in Figs. 6 and 7, and for the purpose of comparison I have 

 drawn Figs. 4 and 5, the first being Gladodus mirahilis, from fig. 2, 

 table 22, of the third volume of the "Poissons Fossiles" ; the second, 

 G. lamnoides, from fig. 16, plate i., of the second volume of the 

 " Geological Survey of Illinois." There can be no doubt, therefore, 

 that these are two specimens of true Cladodi teeth, that is, if there 

 be such a genus as Gladodus, for 1 have a very strong impression 

 that it is only a variety of Hyhodus, but I do not propose to enter 

 upon the consideration of that question at present. 



The remaining fourteen teeth do not present any similarity to the 

 above drawings and descriptions of Gladodus, but do resemble in 

 every particular the description I have given of Hijbodns ; and the 

 comparison of them with acknowledged teeth of Hyhodus will, 1 

 think, remove all doubt that there may yet exist on this subject. 

 Figs. 1 and 2 are copies of Hyhodus cuspidaius and H. plicatalis 

 respectively, as drawn by Agassiz in fig. 6, table 22a, and fig. 11, 

 table 24, of the third volume of his great work. Fig. 3 is a tooth 

 from the Coal Measures of Staffordshire, and was sent by Mr. Ward, 

 of Longton, as a perfect specimen of Gladodus. The specimen is 

 certainly perfect, for every trace of shale has been removed from it, 

 so that it can be examined on all sides. The remainder of the teeth 

 resemble Fig. 3 generally, but differ, as according to Agassiz they 

 should, in having the secondary denticles unequally arranged on 

 each side of the central cone. The arrangement of the fourteen teeth 

 is as follows : in one there is one secondary denticle on one side of 

 the principal denticle, and none on the other ; this secondary denticle 

 is very small, and not well developed, as in Gladodus ; in one there 

 is one on each side, neither of which are developed ; in four there 

 are two on one side, and one on the other; in two, two on each side; 

 in one, three on one side, and one on the other ; in three, three on 

 one side, and two on the other ; in one, four and one respectively ; 

 in one, four on one side, and two on the other. In every case where 

 there is more than one denticle on one side, they decrease, in size, as 

 in Fig. 3. It will be observed that the similarity of these teeth 

 with the description of Hyhodus as given by Agassiz is so complete 

 that in no case are there more than four denticles on one side. 



These facts prove conclusively that Hyhodus existed long before 

 the period assigned by Agassiz and other writers, and was probably 



