308 REV. S. GRAHAM B1RKS 



doubtedly relatively coarse, and the fish therefore belongs to 

 the species M. pygmceus. It seems quite possible that this 

 species may eventually be shewn to be the young of M. 

 hibberti. 



B9* BIO*, and B19* 



There is a wealth of associated head bones in the Hancock 

 Museum. One specimen, B9*, shews the general outline of 

 the parietal region of the skull of the fish, and the decorticated 

 layer of bones forms a striking contrast with the usual ganoid 

 layer. Bio* is part of a smaller skull and shews similar 

 characters. B19* is a similar skull to Bio*. 



Megalichthys hibberti (Ag.) : skull. B1*. (Plate XIII). 



The most interesting skull of Megalichthys in this collection 

 seen in dorsal aspect, however, is one of M. hibberti. 



Certain parts of the skull are well preserved, and the sutures 

 can there be clearly made out. The whole skull, as is usual 

 with remains from the roof shale of the Low Main, Newsham, 

 has been very much crushed, and the specimen before us, 

 while exhibiting both dorsal and ventral surfaces of the skull, 

 is little more than a plate, its thickness being about one 

 centimetre. The central parts of the dorsal surface of the 

 skull are specially well preserved and are of exceptional 

 interest, while the general proportions of the skull in plan can 

 be made out clearly. The skull is much smaller than that of 

 the type-specimen in the Leeds Museum, but it represents a 

 slightly greater proportion of the body surface than the 

 anterior portion of the type-specimen, as it includes some part 

 of the pectoral fin of the right side. 



The parietals are well preserved, and unlike those in the 

 type-specimen, do not end in a slender and jagged process 

 anteriorly. As in the type-specimen, the right bone over- 

 laps the left; each bone is incised by a T-shaped canal, and a 

 short canal seems to run forward from the posterior edge of 

 the right one. 



