16 Dr. R. n. Tmquair on the Oenus Cheirodus. 



Other teeth from the Devonian of Russia were subsequently 

 described by Pander as Cheirodus Jerqfejeivi] and from the 

 resemblance which the palatal tooth-plates of this form bore 

 to McCoy's Conchodus ostreaformis from Scat Crag, he pro- 

 posed to cancel the latter name on the ground that M'Coy 

 had founded it on the palatal tooth-plate of a fish generically. 

 identical with that whose mandibular one constituted Cheiro- 

 dus pes-rance. Cheirodus (inch Conchodus) , as well as Cera- 

 todus, was placed by Pander provisionally among the Cteno- 

 dodipterini. 



On this point Dr. Giinther remarks, " Wherever Dipterus 

 and Ceratodus are placed, thither Cheirodus (M'Coy, Pander) 

 or Conchodus (M'Coy) must follow. But it is probable that 

 this genus is more nearly allied to Ceratodus "*. 



Recently, through the kindness of Prof. Hughes of Cam- 

 bridge, I have been able to examine M'Coy's original speci- 

 men of Cheirodus pes-rance preserved in the Woodwardian 

 Museum ; and, to my surprise, I found it to be nothing more 

 or less than a mandibular dental plate, not of a Selachian, nor 

 of a Dipnoan, but of the Platysomid fish named by Prof. 

 Young, in 1866, Amjjhicentrum. The conformation of the 

 bone and of its ridges is identical with what we find in the 

 splenial element of Prof. Young's fish, as will be seen on com- 

 paring McCoy's figure with that given by myself of the upper 

 aspect of the splenial of Amjyhicentrum gramdosmn (Ann. & 

 Mag. Nat. Hist. (4) xvi. 1875, pi. ix. fig. 8), though before 

 I had seen the original of Cheirodus I should have hesi- 

 tated in affirming their identity. There can, however, be no 

 doubt that they belong to the same genus ; the species is 

 another question. In M' Coy's specimen it will be observed 

 that the tubercles are quite obsolete ; but as regards the 

 number and prominence of these, great differences are found 

 in different specimens of Arnphicentrum granulosum, in some 

 of which they are very slightly marked. Nevertheless I am, 

 upon the whole, inclined to consider the species as distinct f 



Cheirodus^ M'Coy, is therefore not = Cheirodus, Pander, 

 though the latter is possibly the same as M'Coy's Conchodus^ 

 which is undoubtedly a Dipnoous genus. As to the name 

 Chirodus or Cheirodus, I should have preferred to have 

 dropped it altogether, as it was founded on a mere fragment 

 whose nature its describer did not understand ; nor should we 

 have understood it to this day but for the discovery of that 



* Op. cit. p. 557. 



t Mr. W. J. Barkas has recorded the occurrence of Amphicentrum 

 gramdosum, Young, in the Carboniferous Limestone of Richmond, York- 

 shire, Geol. Mac:. (2) i. 1874, p. 431. 



