246 Dr. R. II. Traquair on the Structure 



They were figured and described by Powrie, who considered 

 tlioin, however, to be " hiteral jui^uhir j)hites " — an oj^iuion 

 which, 1 think, lie wouhl scarcely have advocateil save as 

 a corolhiry to his view that the interehivienhir ])hites were 

 " principal " jugulars. The branchiostegal rays are beautifully 

 displayed in a specimen in Lord Enniskillen's collection 

 (IM. XVII. %. 1), in no. 41725 of the British-:Museum col- 

 lection, and also in nos. 134 and 3G0 of the Hugh-Miller col- 

 lection. Twelve of them are counted below each mandibular 

 ramus in Lord Enniskillen's specimen, thcnigh there may 

 have been more ; and of these the anterior one on each side 

 is large, broad, and somewhat triangular in shape, the rest 

 being long and narrow. In a specimen of Amhhiptenis jmnc- 

 t(ttusj Agass., from Wardie, now before me, and of which I 

 have given a diagrammatic sketch in a paper already quoted, 

 exactly the same arrangement of branchiostegal rays or plates 

 is seen, with this exception — that between the two large an- 

 terior ones a lozenge-shaped azygos one is placed immediately 

 behind the symphysis of the jaw ; but of this I have never 

 seen any very clear evidence in Cheirolepis. 



There is very distinct evidence in Cheirolepis of a circle of 

 plates surrounding the orbit, as in Pahvonisciis, but concerning 

 which it is impossible to furnish any more special details ; 

 Pander indeed mentions the arrangement as being formed by 

 one large perforated plate. 



Specimen no. 41310 of the British-Museum collection shows 

 that the tojj of the head was traversed longitudinally by a pair 

 of slime-canals following a flexuous course, similar to those 

 in rahvoniacus ; but I have never seen any specimen showing 

 the individual bones of the cranial roof so well as to enable 

 one to make a satisfactoiy figm-e of them. What I have been 

 able to observe confirms Pander's statement as to the two 

 parietals^ followed by a pair of more elongated frontals. 

 External to these there seem to lie on each side two plates, the 

 posterior of which would seem to represent the squamous plate 

 seen outside the parietal in Lepidosfeus and Amia, while the 

 anterior may coiTcspond to the posffrontal scale-bone seen in 

 the last-mentioned fish. These have nothing to do with the 

 three bones mentioned by Pander as occupying a similar 

 position, and marked 46, x and ?/, in his figures, which, 

 as he himself surmises, undoubtedly belong to the shoulder- 

 girdle and face. The snout seems to have been rounded and 

 blunt ; but no specimen which I liave seen has revealed any 

 thing describable regarding the bones of the nasal region, in- 

 cluding the pramaxilla. The same must unfortunately be 

 also said of the side walls and base of the skull, of the 



