ME. ATTHEY ON CTENODUS OBLIQUUS. 227 



XIV. — On the Articular Bone and supposed Vomerine Teeth of 

 Ctenodus ohliquus ; and on Palmoniscus Hancocki, n. sp., from 

 the Low Main, JVewsham, Northumberland. By Thos. Atthey. 

 With Plate by William Dinning. 



Ctenodus obliquus. 



In a communication made by my late friend, Mr. Albany Han- 

 cock, and myself, to the ' ' Annals and Magazine of Natural 

 History," Ser. 4, Vol. VII., p. 190, we pointed out the close 

 relationship that exists between the mandible of Ctenodus and 

 that of the recent Ceratodus, and showed that the upper outer 

 border of the dental plate of Ctenodus is unsupported. At the 

 date of that communication the articular bone of Ctenodus had 

 not been identified as such. 



For a great many years I had occasionally obtained from the 

 black shale overlying the Low-Main seam of coal at Newsham, 

 near Blyth, Northumberland, an angular bone associated with 

 the cranial bones of Ctenodus, but could not make out to what 

 precise part of the head it might belong, until about three years 

 ago, when Sir Philip Egerton kindly sent me for examination 

 two palatal teeth and a mandible of the recent fish Ceratodus 

 Forsteri, brought from Queensland, Australia. A glance at the 

 specimens showed that the bone respecting which I was in doubt 

 was the articular bone of Ctenodus, corresponding as it did in 

 conformation to the articular bone of the recent Ceratodus. 



Last year (1874) I was fortunate enough to find, also at New- 

 sham, two fine specimens of Ctenodus ohliquus with this very ar- 

 ticular bone in situ; and one of these is figured on Plate V., 

 figs. 1 and 2. 



The bones differ in size, being from three-quarters of an inch 

 to four inches in length. The inner side of the mandible is 

 formed by the ramus or body of the jaw surmounted by the 

 teeth ; and these at their upper margins arc turned outwards 

 and flattened, and project towards the upper border of the arti- 

 cular or external piece. The narrow elongated space left be- 

 tween the two bones of the fossil at this part would necessarily 



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