ON THE VOMERINE TEETH OF CTENODTJS. 117 



statement concerning the structure, we will see hereafter, is not 

 altogether correct. Accompanying the above-quoted paper were 

 illustrations o£ the vomerine teeth, which do not differ from those 

 I had figured a year previously. Mr. Atthey does not state why 

 he supposes these teeth to belong to Ctenodus but he leaves it to 

 be inferred that his belief is founded upon discovering them 

 often accompanied with undoubted remains of Ctenodus^ nor 

 has any other proof than this been yet obtained ; still, knowing as 

 we do that Ctenodus is similar in its details to Ceratodus, we are 

 justified in supposing that it also possessed vomerine teeth. 

 Ctenodus is also very closely allied to JJipterus, and Dr. Griinther 

 considers that he has evidence to show that the latter fish 

 possessed vomerine teeth, for he has found a head with fang 

 cavities situated just w^here the incisor teeth should have been ; 

 the vomerine teeth of Dipterus, however, have never been dis- 

 covered. Should this statement of Dr. Griinther be correct, it is 

 rendered more probable that Ctenodus was armed with similar 

 oral appendages. To the facts that these petaloid- shaped teeth are 

 found associated with remains of Ctenodus, that the allied fishes 

 Ceratodus and Dlpterus have vomerine teeth, we must add that 

 they have a certain degree of resemblance in form to the known 

 incisor teeth of Ceratodus which are thus .described by Dr. A. 

 Griinther: — "The vomerine teeth are broad and rather low laminae 

 with a convex and trenchant margin, the outer or posterior part of 

 which slightly serrated. Each lamina is 13 millims long, and iu 

 the middle 5 millims deep. They are inserted in an oblique 

 direction to the longitudinal axis of the vomer, and meet in the 

 middle at a right angle ; being implanted in cartilage, they are 

 slightly movable." 



A vomerine tooth of Ctenodus " presents some rather peculiar 

 characteristics ; it is 2-5ths of an inch in height, about the same 

 dimensions from side to side at the broadest part, which is near 

 the superior border, and 3-lOths of an inch in thickness at the 

 lower portion of the base. The tooth presents two portions, a 

 crown and a base, which are only distinctly separated on the 

 posterior surface ; I shall not, therefore, describe them separately, 

 but take the tooth as a whole. The posterior surface (Fig. XIV) 

 is somewhat triangular in shape, with the ?43ex pointing down- 

 wards ; it is concave from above downwards, the concavity being 

 most pronounced near the lower border of the tooth, where the 

 apex of the triangle is bent backwards rather abruptly ; the 

 upper portion of this surface is smooth, shining, and minutely 

 pitted; the lower is irregularly pitted, the depressions being 

 comparatively large, the raised portions round the pits give this 

 part of the surface a coarsely reticulated as well as pitted 

 appearance. The anterior surface (Fig. XA'"!) is divided into a 

 crown and a base ; the crown is convex from above downwards 



