232 Miscellaneous 



and usually tuberculate ; the molars are usually single-rooted, in 

 close-set series which diverge as they extend backward, with crowns 

 which vary in form, but are commonly wider than long, and usually 

 have the external and internal cusps more prominent than the other 

 tubercles on the crown. 



The group is based chiefly upon the genera Gomphognathus, known 

 from skulls, a vertebra, and fragments of limb-bones ; THrachodon, 

 known from skulls only ; and Microgomphodon, in which the canine 

 teeth are no larger than the incisors. The last genus appears to 

 make known the more important parts of the skeleton. 



These specimens, collected by the author at Lady Prere, by Dr. 

 Kannemeyer near Burghersclorp, and by Mr. Alfred Brown near 

 Aliwal North, are all from the Upper Karroo rocks on or about the 

 horizon of the Coal Beds. 



Of Gompliognatlms there is a complete skull, with the lower jaw 

 attached, about 9 incheo long, a second skull which displays the 

 palate, and a separate lower jaw in connexion with part of the back 

 of the skull. These specimens show four incisor teeth in each pre- 

 maxillary bone, with sharp lateral serrated borders. The mandibular 

 canine is covered when the jaws are closed. The maxillary canine 

 is a powerful tooth ; its extremity is worn obliquely. There appear 

 to be six premolar teeth, all contained in a length of half an inch. 

 The maxillary teeth are packed in close succession, as in Rodents. 

 There are nine molar teeth. In the middle, where they are largest, 

 four occupy the length of one inch. The contour of the crowns of 

 these molars is convex from front to back, as in many mammals ; 

 and in this genus they are all behind the hard palate. The external 

 cusp is prominent, and a ridge descends inward and backward from 

 it upon the large flattened ledge of the crown, which is worn almost 

 level, as though there Were a rodent-like horizontal movement of 

 the lower jaw. 



A lumbar vertebra, found in developing the back of the skull, 

 may possibly belong to this genus. 



With the skulls a right humerus was found, which is 5| inches 

 long. It shows the reptilian transverse elongation of the proximal 

 articulation, combined with characters which are paralleled in the 

 marsupial mammals and Carnivora. 



The genus Microgomphodon is known in the first place from a skull 

 2| inches long, shaped much as in Galesaurus, but distinguished by 

 the comparatively large size of the front pair of mandibular incisors 

 and the strong, conical, pointed character of the incisor teeth. The 

 canine teeth are not differentiated from the incisors. The molars 

 show in lateral aspect small blunt cones, but on their palatal aspect 

 have flattened crowns with many small cusps. All the teeth have 

 short roots. There are three incisors on each side in both the man- 

 dible and skull, one canine, and five molars. 



There is ground for associating with this genus an imperfect 

 skeleton, which, in addition to indicating ten early dorsal ribs and 

 fourteen lower dorsal vertebras and ribs in advance of the acetabu- 



