92 MESSES. HANCOCK AND ATTHEY ON 



sections of minute jaws ; and, unless clearly understood, may 

 readily lead to error. The diagonal section of a quill illustrates 

 this very well. 



The bone-cells of the jaw of Rhizodopsis are quite as Batra- 

 chian as are those figured of the ■pseudo- G astrodus ; and so are 

 those of Megalichthys, and many other sauroidal fishes. 



There is, then, no evidence in the paper referred to of a mi- 

 nute air-breathing Batrachian of the age of the lower seams of 

 the Northumberland Coal Field, the so-called genus Gastrodus 

 being resolvable into Rhizodopsis sauroides, a Ganoid fish. 



Ctenodus ceistatus. 



Since the publication of the paper on Ctenodus,'^ the matrix 

 has been carefully removed from the upper side of the large sphe- 

 noid bone of this species by which the size of the fish was esti- 

 mated. And now this interesting specimen reveals to us the 

 cranial bones of the occipital region in an undisturbed and ex- 

 cellent state of preservation. The whole of the bones of one 

 side are almost perfect, so that there is no difficulty in restoring 

 this portion of the cranium, the constituent bones of which are 

 arranged exactly as they are in the figure of the " cranial buck- 

 ler" oi DijJtei'us given by Hugh Miller in his " Footprints of the 

 Creator." 



The bones vary little in size, and, with the exception of the 

 central occipital and parietals, are most irregularly pentagonal. 

 There are three occipitals ; the central one is not much larger 

 than the lateral ; the former is nearly as wide as it is long, and 

 is seven-sided, with the anterior margin a little pointed in the 

 centre, and the posterior margin nearly straight. The lateral 

 occipitals are connected with the postero-lateral margins of the 

 central occipital, and, diverging in front, admit a bone on each 

 side, which is wedged in between them and the antero-lateral 

 borders of the central occipital and the external margins of the 

 parietals. External to these bones, and in connexion with their 



" Annals and Magazine Natural History," Feb., 1868. 



