Dysganus encaustus, Gen. et sp. nov. 



Char. Gen. — A large number of teeth exhibit the characters of 

 this genus, which is a peculiar form of herbivorous Dinosauria. 

 The crowns are compressed, so that the fore and aft diameter 

 much exceeds the transverse. The body of the crown is a flattened 

 shaft of dentine, one face of which is the denser, and produces the 

 cutting, edge. This face is flat or weakly keeled, while there are 

 two other faces uniting at an open angle, thus giving a subtri- 

 angular section. On each of these faces is adherent a shaft of 

 cementum-like material of a dense character, whose external face 

 is longitudinally concave. These inclose between them on the 

 median line a deep groove, which expands below into a wide con- 

 cavity, which appears to be enlarged as the age of the tooth in-" 

 creases preparatory to shedding. The other parts of the base of 

 the crown below the cutting face, are inclosed in a rather thick 

 deposit of rugose cementum, which rises a distance on the sides 

 of the tooth. 



The method of replacement of the teeth in this genus appears 

 to resemble that of Cionodon, except that there is no indication 

 of the existence of as many series in the transverse direction. The 

 longitudinal grooves in the anterior and posterior cement columns 

 are probably occupied by the borders of the apices of successional 

 teeth. The presence of these columns, etc , distinguishes this 

 genus from that and other allied genera. 



Char. Specif. — The cutting face is more or less concave, and is 

 impressed or sunken, its lateral borders, and the cement of the 

 basis, projecting beyond it. The inferior border is also usually 

 oblique, that of one of the sides rising diagonally. In the same 

 propoi'tion, a weak keel is also unsymmetrically placed, lying close 

 to the opposite border, and dividing the face into a wide and a 

 narrow concavity. The oblique border is also incurved, the edge 

 of the posterior cement column curving round the cutting face of 

 the dentine. The latter is delicately rugose in unworn specimens. 

 The external basal cementum rises highest on the incurved border 

 of the crown ; its surface is minutely rugose, the rugosity being 

 generally punctiform. It is also of a different color from the 

 dentine in the specimens as preserved, and is occasionally found 

 nearly worn away. The edge of unworn teeth is not serrate. 



