NEW FOSSIL RKPTILKS. 865 



diastema between the last incisor and the canine is only 2 mm. 

 The canine measures at its base 6 mm. by 5 mm. The molars 

 are at least 7 in number, and are small, pointed but apparently 

 unserrated teeth. The seven occupy 17-5 mm. Between the 

 canine and the first preserved molar is a diastema of 9 mm. 



The lower incisors are preserved in section and are 4 in number, 

 the 4th being inside the line of the others. The canine is far 

 forward and small and rounded, the section measuring 3'5 mm. 

 in diameter. 



6 1 7(? 8) 



The dental formula is probably i. -, c. r, m. -^ — . 



ICTIDOGNATHUS HEMBURYI, sp. n, (PI. XCI. figS. 10, 11.) 



This new species is founded on four imperfect snouts found by 

 Mr. H. J. Hembury at Beaufort West. There are minor 

 differences between the snouts probably due to crushing, to age, 

 and possibly to sex, but I believe they all belong to one species. 

 To avoid any possibility of confusion I shall take the skull 

 (fig. 10) as the type. It is the best preserved specimen but does 

 not show the molars satisfactorily. 



As in Alojyecorhinibs the snout is broader than deep. This 

 is probably also the case in Ictidognathiis parvidens, but the only 

 known specimen of this species is considerably crushed. From 

 the front of the snout to the front of the orbit the measurement 

 is 42 mm. The antero-posterior diameter of the orbit is 18 mm. 

 The interorbital region is 19 mm. across. The measurement 

 across the snout at the canine region is about 27 mm. 



The premaxillary is a very small bone forming the anterior and 

 lower margins of the nostril. It carries six small pointed, rounded, 

 smooth incisors. I fail to detect serrations on any of them. The 

 six incisors occupy a space of 10 mm. 



The septomaxillary is unusually large and forms as large apart 

 of the facial surfaces ns does the premaxillary. There is the same 

 foramen between it and the maxillary seen in typical Thero- 

 cephalians, but it is I'elatively smaller than in other forms. 



The nasal bone is well developed and is interesting from the 

 fact that it is only very little broader behind than in front. 



The maxillary is typically developed. As in so many Thero- 

 cephalians, the centre part of the bone is markedly pitted as if for 

 the accommodation of glands or sense organs. In the same region 

 there are numerous foramina passing into the bone, and some of 

 these foramina lead back into a canal in the bone. As there is 

 no large foramen in the maxillary bone which might be regarded 

 as the foramen for the maxillary branch of the Vth nerve, I 

 think it probable that this nerve subdivides in the maxillary 

 bone and comes to the surface by a number of small foramina, 

 and that the pits w^ere for sense organs which were supplied by 

 this nerve. The tactile vibrissfe of mammals, or the remarkable 

 sense organs of the beak of Orydthorhynchus may be the modified 

 homologues of these supposed ancestral organs. 



