394 Davis — On the Fossil Fish of the Cretaceous Formations of Scandinavia. 



have a decidedly sygmoidal curvature combined with a peculiar twist outwards 

 towards the apex. 



The length of the anterior teeth is 0*05 m., the lateral diameter, midway be- 

 tween the base and the apex, is 0'012 m. ; the lateral margins are produced so as 

 to form a fine cutting surface, and gradually converge to an acuminate apex ; 

 towards the base the tooth thickens, and rapidly expands to a diameter of 

 0-025 m. The enamelled surface is invariably smooth near the point ; in some 

 examples the internal surface maintains this character quite to the base, whilst 

 the external is only slightly grooved ; in others deep channels extend from the 

 base far towards the apex on both the internal and external surfaces, usually more 

 pronounced on the latter. The channels are divided into more numerous, but 

 smaller, grooves at the base. The external surface of the anterior teeth is less 

 rounded than the internal one ; in those teeth situated posteriorly the curvature 

 of the two surfaces is about equally well developed. The root is not well 

 preserved in any of the Swedish examples, but suificient remains on some of the 

 specimens to show that it was much wider than the crown, and that the internal 

 surface was produced so as to form a prominent median bulb. The posterior 

 teeth are less deeply grooved, and more rapidly and uniformly converge to a 

 point than the anterior ones: an average length is 0'03 m., with a lateral diameter 

 of 0'017 m. at the junction of the enamelled surface with the root. 



A beautifully preserved specimen, showing the crown and root of a tooth, 

 which occupied a lateral position in the jaw, occurs in the Mineralogical Museum 

 at Copenhagen. It is embedded in a matrix of the coraline limestone or chalk 

 of Faxe. To some extent this is unfortunate, because the internal surface of the 

 root is hidden by the matrix ; but it is very probable that the fact of its being 

 attached to the matrix has preserved the crown and root intact. The examina- 

 tion of many hundreds of specimens has shown that the attachment of the crown 

 to the root is more or less fragile, and the root being apparently less easily 

 detached from the matrix than from the crown the two parts are rarely found 

 associated. It may be imagined, however, that a more careful search in the 

 limestone forming the matrix at the base of the crown would result in the 

 discovery of many other examples of the root. The height of the crown in this 

 specimen is 0'035 m., and its width across the exposed external surface is 

 0-012 m. The crown is curved slightly backwards, and at the same time 

 exhibits a sygmoidal curvature of the inner and outer surfaces. The outer 

 surface is deeply grooved from the base upwards ; the inner one smooth ; the 

 margins have a sharp cutting edge, and the apex is acuminate. The root extends 

 at an obtuse angle from each margin of the crown, forming a pair of processes 

 expanding to a diameter of 0-032 m., nearly equal to the height of the crown. 

 The under sm-face of the root is only slightly concave. The total height of the 



