308 Ilerr F. Siebenrock on the 



acustici for tlie ramus cochlearis, which in the other lizards 

 leads into the cochlea, we find no trace whatever in Hatteria. 

 On the upper border of the otosphenoid are situated two holes, 

 the foramen canalis semicircularis sagittalis in front and the 

 foramen canalis semicircularis horizontalis behind at the 

 base of the processus posterior. In tliis case the two holes 

 themselves are not connected by a cleft, as we find them to 

 be in the paroccipital, but each hole (PI. XLV. fig. 10, J and 

 a") is in connexion with the anterior ampullary cavity, so that 

 it looks as if the holes and their canals have arisen as a result 

 of the laying together piece by piece of the walls of the 

 vestibulum, a condition which is seen in Hatteria alone, as 

 was pointed out above in the case of the paroccipital. 



On the inside of the otosphenoid, behind the incisura oto- 

 sphenoidea and in front of the anterior vestibular wall, lies an 

 oval pit, which contains the foramen nervi acustici above and 

 the much smaller foramen nervi facialis below. 



1 have observed in many lizard skulls that the basioccipital 

 remains longest separate from the rest of the occipital bones. 



In Hatteria the converse appears to be the case, for here 

 the basioccipital is always already united by synostosis with 

 the two pleuroccipitals, when the remaining bones are still 

 distinctly divided by sutures. 



In the case of the sphenoid bones at first merely the pro- 

 cessus anterior inferior of the otosphenoid coalesces with the 

 processus alaris of the basisphenoid, while the two bones 

 behind the crista otosphenoidea still continue separated by a 

 distinct suture. 



III. 



The parietal of Hatteria is described by Giinther [lac. cit. 

 p. 2) as follows: — "The parietal bone is very narrow and 

 elevated into a strong mesial crest, which, although appearing 

 simple in an individual of advanced age, evidently consisted 

 of two lateral halves in youth," c^c. In opposition to this 

 Briihl writes {loc. cit.): — "The parietal, which even in 

 younger skulls already appears unpaired, although it may 

 well be paired in the embryo," Sec. Five Hatteria skulls 

 disarticulated by me have yielded the result that the parietal 

 remains paired not merely in youth, but throughout lite. In 

 the case of a skull, too, in which all the sutures of the bony 

 cranium had already completely disappeared, a proof that 

 the specimen was certainly already adult, the parietal fell of 

 itself into two halves after carelul maceration. These are 

 united in Jhittiria by synchondrosis, and not, as in the Asca- 



