ON MEGALICHTHYS 309 



The bones corresponding to the post-frontals and squamosals 

 of the type-specimen are two, not four in number. These bones 

 are well preserved, and on the inner side each exhibits a suture 

 which begins at about the same point as the division in 

 the type-specimen ; but this suture dies away about half way 

 across the bone, so that there are but two " compound 

 squamosals " (post-frontal -f- squamosal) present, one on either 

 side of the parietals. On the right side the suture and a crack 

 give the appearance at first sight of a dividing suture, but on 

 the left there is only the interrupted suture. The left squamosal 

 element shews a transverse canal, and there are indications of 

 the same feature in the right bone. There is a small process 

 of the right " compound squamosal " corresponding to the 

 portion of the skull which Agassiz took to be the nasal. This 

 process, together with three small bones, fills the space which 

 intervenes between the " compound squamosals " and parietals 

 and the frontals. One of the three small bones corresponds 

 in position, on the left side, with the process of the right 

 " compound squamosal," while in close juxtaposition, and 

 between this small bone and the process, is the smallest of the 

 three bones. The third small bone is placed in a median and 

 anterior position. 



The frontals are well preserved, and each exhibits a canal 

 with a curved course, as in the type-specimen. The " com- 

 pound ethmoid " is much cracked, and it is consequently 

 difficult to determine whether or not it is single. There is a 

 large oval depression on either side of the shield near its 

 border ; and a little nearer its anterior end, and slightly more 

 median in position, there is a small raised area on either side 

 of the skull which appears to have been caused during the 

 crushing of the fossil. These areas were perhaps raised by 

 the crushing up of two laniary teeth into the roof of the buccal 

 cavity. On the left anterior border of the " compound 

 ethmoid " is a small notch, perhaps corresponding to the nasal 

 opening noticed in the type-specimen. 



Much displacement has taken place in the sub-orbital and 

 more posterior regions, and it is difficult to determine the exact 



