164 Br. W. J. Barkas — Hyhodus, a Coal-measure Fish. 



selves to the fauna or flora of the formations that are most exposed 

 in their localities, either by nature or by the hand of man. Thus 

 palseontologists, living in a district where the extraction of Coal is 

 the chief employment, collect and study the remains existing in the 

 Carboniferous strata, and often their researches are narrower even 

 than this, being confined either to the true Coal Measures or to the 

 Subcarboniferous Limestones. In consequence of this limitation of 

 inquiry, there is often great ignorance of what passes in districts 

 where other formations are worked, and it may very well happen 

 that the remains of the same fish or reptile may be found in dif- 

 ferent formations, but yet be named differently and considered as 

 distinct genera. Errors also arise from collectors following the 

 dogmatic statement of some distinguished palseontologist. In this 

 manner, Prof. Owen caused great confusion among Coal Measure 

 inquirers when he published his " Dental Characteristics of Fishes," 

 for in that work he founded numerous new genera upon very small 

 data indeed. The confusion in this case, however, was not of long 

 duration; for Messrs. Hancock and Atthey (the latter having probably 

 the largest collection of Coal Measure Vertebrate remains in the 

 Northumbrian district) immediately showed most conclusively, from 

 specimens in their possession, that every tooth named by Prof. 

 Owen had either been named previously, and of course differently, 

 or was simply a tubercle, and not a tooth. I also can emphatically 

 confirm their conclusions. In the same manner I consider the state- 

 ment of the late Prof. Agassiz, that the fish Hybodus was never 

 found below strata of Triassic age, while its ally Cladodus existed in 

 the Carboniferous period, has influenced palaeontologists to believe 

 that all teeth having the characters of Hybodus, and found in the 

 Coal Measures, could not be Hybodus, but Cladodus. The belief 

 that the remains of the former fish are never found in the Coal 

 formation has hitherto been universal ; yet I have seen specimens 

 gathered in Northumberland and Staffordshire that cannot be dis- 

 tinguished in any way from the descriptions and drawings given by 

 Agassiz in his excellent work " Poissons Fossiles." In fact that is 

 the only work, combining both Hybodus and Cladodus, that I have 

 access to, in which I can find any definite descriptions or drawings, 

 and these are so good that I cannot do better than quote his words 

 and copy his drawings in order to prove that remains of Hybodus are 

 found in the Coal Measures. In the second volume of the " Geo- 

 logical Survey of Illinois " there are excellent descriptions and 

 engravings of Cladodus. 



In the third volume of the " Poissons Fossiles" Agassiz says, with 

 regard to the geological position of Hybodus, " Nous voyons des dents 

 d'Hybodes apparaitre pour le premiere fois dans le Muschelkalk, se 

 Gontinuer dans le Keuper, et devenir tres-nombreuses dans le Lias 

 et dans les terrains inferieur du Jura. II n'y a que la craie qui ne 

 nous ait pas fourni de dent qu'on puisse rapporter au rayon de la 

 craie de Lewis, que j'ai decrit sous le nom de Hybodus sulcatus. 

 Enfin les Hybodes sont compl^tement etrangers aux terrains tertiaires 

 et k I'epoque actuelle, qui ne contiennent ni rayons ni dents de ce 



