PROF. OWEN ON THE SKULL OE MEGALOSAURTTS. 337 



and missing part of the smaller premaxillary tooth gives two inches 

 of length to this tooth ; the implanted remainder of both teeth has gone 

 with the supporting bone. In advance of the larger premaxillary 

 tooth is an elliptical cross -fractured basal part of a third (the an- 

 terior) tooth, showing a long diameter of nearly half an inch. 



Ten teeth are preserved in the maxillary bone. Between the 

 foremost, third, and fifth are crowns of successional or undeveloped 

 teeth. Of the foremost of these (second in the series) the apex only 

 of the crown has appeared above its socket ; the rest of the tooth 

 is exposed by removal of the socket's outer wall : a length of 

 enamelled crown of 2 inches 5 lines is thus shown. The length of 

 the protruded crown of the first maxillary tooth is 1 inch 9 lines ; 

 that of the third tooth is 2 inches 3 lines ; its total length is 5 

 inches. Of the fourth tooth the apical half-inch of the crown is 

 protruded : the total length exposed in the quarrying is 3| inches. 

 The similarly shown length of the fifth tooth is 4 inches 9 lines, 

 that of the enamelled crown being 3 inches. The sixth tooth shows 

 2 inches of free enamelled crown, and 2| inches of the rooted 

 cement-clad part, the latter exposed by loss of the bone. The 

 seventh maxillary tooth is represented by a smaller proportion of the 

 protruded crown. The eighth tooth is a functional fully developed 

 one, but of smaller size than the third and fifth. The apical half of 

 a somewhat smaller crown of a ninth tooth has emerged ; and behind 

 this is the indication of a fully developed tenth tooth, not larger 

 than the eighth. I cannot predicate with confidence the existence 

 of an eleventh maxillary tooth. The crown of such exposed tooth 

 on the transversely fractured surface of the block may have come 

 from the lower jaw. 



Of the maxillary teeth the four or five hinder ones are suborbital, 

 the three front ones are subnarial ; the three intermediate teeth, in- 

 cluding those with longest and largest crowns, received the support, 

 in biting action, of the base of the facial process, a. 



At the fore part of the orbital cavity are two thin osseous plates, 

 e, e, convex outwardly, of subtriangular form, with the apex 

 naturally cut off so as to contribute half the circumference of a 

 protruding circular space, half an inch across, exposing the matrix : 

 the margin of this circular aperture is slightly raised. These 

 plates show, or have been resolved into, three lamellae, each less 

 than a millimetre in thickness : part of one lamella, and an impres- 

 sion of another, are shown on the slab containing the teeth and bones ; 

 parts of three lamellae of one of the plates adhere to the counterpart 

 block. The matrix near what seems to be the pupillary border is 

 stained of a darker colour than the rest. I deem it probable that 

 we have here an indication of the eye-ball of the Megalosaur, and 

 that the pupillary corneal part of the ball was strengthened by a 

 few large sclerotic plates. The indicated diameter of such eye-ball 

 is two inches. The attention devoted to this part of the fossil was 

 requisite to determine whether it might be part of a lacrymal bone 

 or of the sclerotic. 



The orbit in its great relative size and departure from the usual 



