CHAMAL DUCKLER OF A DIPXOAX FISH KTHKHIIx;!:. I'M 



iluwii, and is ('\eii then, faint and incuiispiciiuus, and there are 

 no tooth-like projections ^•isi1)le so far as the lower portion of the 

 specimen has been de\elopefl. Tlie ends of the lateral projecting 

 t>ortions of the lal)iiun are slii;htly eiilarijed and hlunt. but not 

 incurved. 



The pt)lvi;(inal cranial plates are not bilaterally synnnetrical, in 

 fact they are verv^ irregularly arranged. Tn Dipf'i-ti.,^, even, 

 Traquair says" "it is ditticult to trace any exact correspondence 

 between them and the cranial roof-bones of ordinary (ianoids and 

 Teleostei." I certainly hoped to be able to institute a comparison 

 between these cranial plates and those of Dlptirux as restored by 

 Dr. C. H. Pander/ but those of <nu' fossil do not appear to 

 correspond with the arrangement shown in liis restoration : even 

 in the latter they are not wholly bilaterally symmetrical. For 

 instance, assuming Panders restoration to represent the complete 

 cranial buckler of Dipft'vns, his me<lian occipital is one of the 

 largest plates of the series, and is po.steriorly terminal. On the 

 other hand, the lai'gest plate in the median line of our buckler 

 is not terminal and tiie two flanking plates on either side do not 

 correspond in outline or size witli one another. In Panders 

 figure the anterior semicircle is ctjmposed of thre( lai'ge i)lates, a 

 central and two lateral, but these ai-e not shown in Hugh Millers 

 repi-esentatioii'^ of the same. In the in-esent instance the dorsal 

 surface of the snout evinces no sign of subdivision that T can 

 detect, nor does that of (r. icnodinirdi, Traq. 



As c<mipared with the snout of G. >oo(>fhc(ir<Vi, that of our 

 specimen is less dome-like, much Hatter abo\"e, and with a greater 

 degree of spread between the rounded lateral projections in propor- 

 tion to its size. This less dome-like outline is a{)i)arent in a side 

 view (PI. xxviii., fig. 2) if tlie fossil be placed in its natural position, 

 corresp(jnding with Tra(piair's fig. M, PL xi\-. .Speaking in general 

 terms it may be said that the labial features of ''/. susfoiiilchi ai-e 

 not .so pronounced as those of (t. iroodivardi — the nasal ojjenings 

 are not so deeply excavated, nor is the median emargination 

 visible until the buckler is seen from below. 



Tilt- history of G. iroodicardl is a curious one. It a})[)ears that 

 when Mr. C. Konig was Keeper of the Geological Department of 

 the liritish ^Museum, the specimen came under the notice of the 

 illustrious Agassiz, who regarded it as the intermaxillary l)one of 

 Miuinliclitln/x. Years after Dr. H.Woodward called Dr. Tra- 



■• Tnuiuaii-— Ann. Mag. Nat. Hist. (5), ii., 1878, p. it. 

 ' Pander -Die Ctenodipterinen, 1S58, pi. i., f. 1. 

 •" >riller lu.otsteps I8tli ed., 1871. )). .",8, f. 20. 



