344 



MR. R. LYDEKKER ON A LABYRIXTHODOXT SKULL 



Huxley in the Trans. Roy. Irish Acad. vol. xxiv. pi. xxiii. fig. 2, 

 under the name of Erpetoceplialus rurjosus^ it will be evident that 

 the two are generic-ally identical. The last-named skull has, how- 

 ever, a length of only 2*5 inches, and since a number of specimens 

 have nearly the same dimensions and never exceed them*, it is 



SJcuIl of IchtJiyerpetum liihernicum. | natural size. 



1. Outline of the cranium : e^, epiotic cornu ; mi, auditory slit ; or, orbit; 



na, nares. 



2. Left mandibular ramus. The extremity of the premaxilla is seen to 



be bent down upon the symphysis. 



probable that its superior size would alone serve to indicate the 

 specific distinctness of the present specimen. 



If, however, the two figures be compared, it will be seen that the 

 auditory slits are deeper, the epiotic cornua less produced out- 

 wardly, and the interorbital bar relatively less wide. In the speci- 

 men before us, I therefore think it most probable, although I cannot 

 be absolutely certain, that we have an example of a distinct species, 

 which I propose to provisionally name IclitJiiierpetinn hihernicum ; 

 the generic identity of Ei'peiocepJialus with IchtJiyerpetum having 

 been shown by myself t on a previous occasion. 



The interest of the specimen does not, however, lie in the question 

 as to whether or no it indicates a new species, but as regards the 

 relationships of the genus to which it belongs. In the work just 



* In the British-Museum Catalogue, from the belief that the specimens were 

 imperfect, the length is given as about 3*1 inches. 



t Cat. Foss. Kept. & Amphib. Brit. Mus. pt. iv. pp. 168, 169. 



