486 On Species of Saurocephalus. 



the teeth extend backward somewhat farther, so that there 

 must have been forty. At some time in the career of its 

 owner the riglit maxiUa has been fractured obliquely across 

 its middle, and this accident lias affected the neighbouring 

 teeth. One of these has thus become exposed nearly half- 

 way to the tip of the fang. This exposure reveals the fact 

 that the fang is faceted, as it is in S. lanciformis. The 

 great length of the maxilla distinguishes this species from 

 both S. lanci/oi'mts and S. dentatus, and the facets on the 

 teeth distinguish it from Cope's S. arapahoviiis. Mr. Stewart 

 has not described the condition of the fang of the teeth of 

 his S. dentatus. 



In fig. 5 p.c. represents the palatine condyle; p.c' the 

 anterior palatine condyle which was applied to a surface like 

 that shown in fig. 3 at mx. 



I propose to call the fish above described Saurocephalus 

 immphagus*. 



It has been supposed that the foramina, situated one 

 opposite each tooth and on the mesial face of the maxilla and 

 of the dentary, are for the transmission of nerves and vessels 

 to the teeth. Richard Owen f seems not to have so regarded 

 these foramina. He believed that they " lead to the cavities 

 containing the germs of the successional teeth." Tiie latter 

 probably began their development in, or at the bottom of, 

 these foramina ; but they soon passed more deeply into the 

 bone. In fig. 1 at t there is found a developing tooth whose 

 tip is on a level with the row of foramina ; but its root 

 extends high up into the bone. Nerves and vessels entering 

 the tooth by way of the foramina alluded to would have to 

 take a very tortuous course. The functional tooth imme- 

 diately below the young tooth figured seems already to have 

 suffered some reduction of its fang. 



The germs of the teeth of the Saurocephalidge did not gain 

 a lodgment in the bones of the jaws in the same way that the 

 teeth of the higher vertebrates did. In the latter the fangs 

 were first planted in grooves in the dental borders of the 

 bones ; and we must suppose that these grooves, at first 

 shallow, have, in successive generations, deepened and be- 

 come portioned off to form sockets. In the Saurocephalidt« 

 the teeth, developing originally on the dental border, have 

 gradually migrated away from this border, on the mesial face 

 of the supporting bones, and, by means of the foramina de- 

 scribed above, have made their way through the mesial wall 



* Inde ruunt alii rapida velocius aura, 



Pampbagus et 



Ovid, Met. Bk. iii. 1. :>09. 

 t Odontography, p. 131. 



