ON MEGALICHTHYS 3II 



isolated bone is seen in a median position in front of the 

 parietals. Each parietal is incised with two canals, which 

 differ slightly from those of M. hibberti in disposition in that 

 they are not set at right angles to one another. The left 

 squamosal is also incised with a transverse canal, and the 

 posterior border of the left parietal has a slight incision 

 running forwards. Small depressions occur irregularly on all 

 the bones, while the whole of the surface is furnished with the 

 tuberculation characteristic of the species M. coccolepis. 



Megalichthys coccolepis: B3*, portion of skull. 



We pass on to B3*. This specimen of M. coccolepis shews 

 parts of the parietals and neighbouring bones, and although 

 the skull is not in such good condition as B2* several points 

 of interest can be made out. The parietals shew the central 

 canals disposed in the same way as in B2* and the transverse 

 canal appears on the right squamosal. The suture between 

 the post-frontal and the squamosal is clearly defined on the 

 right side, and the characteristic tuberculation of the species 

 is seen on the ganoin. Here and there the bony layer is 

 exposed, and the canals can be traced across parts of this in 

 the right parietal and squamosal. 



Megalichthys hibberti : B4*, portion of skull. 



B4*, a portion of a skull of the species M. hibberti, is of 

 interest because here the left " compound squamosal " perhaps 

 has an incomplete suture between the two elements. As the 

 specimen is not in a very good state, the surface of the bone 

 being covered with a thin coating of shale, it is possible that 

 the left suture may be present. There appears to be a com- 

 plete suture in the corresponding position on the right side. 

 The "nasal" of Agassiz is here median in position, and is 

 the termination of a process of the left post-frontal element. 

 At points where sutures might have been expected there is a 

 slight depression on the surface of the bone. 



