NO. 1660. SKULL OF TRlCLliATOl'S—JlAY. ]^Q5 



a distance of 65 mm. below the surface of the brain, just behind the 

 pituitary fossa. The bone in the region of this fossa has been dam- 

 aged and rephiced by white plaster. The fossa probably occupied 

 the white area indicated by pit. f. in Plate 2, fig. 2. Its supposed 

 hinder end is indicated there by a dotted line. 



The writer has not been able to see the opening for the sixth nerve 

 in this specimen. Possibly it pierced the bone farther forward than 

 in T. sei'mtus, at a point Avhere the bone is damaged. 



This specimen furnishes no certain evidence regarding the opening 

 of the temporal fossa into the so-called post-temporal foramen. The 

 upper parts of both temporal fossa? have been filled with plaster, in 

 order to strengthen the specimen. On each side there is a passage 

 from the temporal fossa into the cavity, or sinus, into which the so- 

 called post-temporal foramen opens. On one side this opening seems 

 to be partially artificial. On the other side it seems to be natural, 

 but is possibly the result of accident. Here the opening is about 

 large enough to permit the passage of one's finger. 



THE BKAI^-CASE OF IGUANODON. 



Hulke " has described' a brain-case believed to belong to Iguanodon. 

 The same specimen has been redescribed by Dr. C. W. Andrews, of the 

 British Museum of Natural History.'' A few remarks will be made 

 on these descriptions. 



Hulke has designated a part of the axis of the skull as equivalent 

 to the basisphenoid and the presphenoid.^ It is evident that the 

 presphenoid is present. The basisphenoid appears to extend forward 

 to the notch above the letters ii. That part of the axis beyond this 

 notch is quite certainly the orbitosphenoid. It includes the optic 

 foramen. 



Judging from Hulke's and Andrews's accounts of this skull the 

 ophthalmic branch of the fifth nerve left the common stem after the 

 latter had passed wholh^ through the brain-case, and it then ran for- 

 ward in a groove on the outer surface of the bone. In Triceratops 

 the beginning of the canal that transmits this branch is deeply buried 

 in the bone. 



What Andrews regards as a foramen for transmitting a branch of 

 the internal carotid artery into the brain cavity the present writer 

 holds to be the exit of the seventh nerve. The nerve descended along 

 the groove described by Andrews. What in Andrews's figure appears 

 to be a foramen placed 18 mm. above the optic foramen may cor- 

 respond to wdiat in Tricevatops is thought to be an opening for the 



« Quart. Joiirn. Geol. Soc, XXVII, 1871, p. 100. 



6 Ann. Mag. Nat. Hist., Otli ser., XIX, p. ,585. 



« Quart. Journ. Geol. Soc, XXVII, 1871. pi. xi, figs. 1 , 2, hps. 



