1%93.] OSTEOLOGY OF LEPIDOTL'S AXD DAP.:UIITS. 565 



border of the crauiuui ; but Dapedtus at least is distiiiguislnJ from 

 Amia and approximated to Lepvhstcas by the course of the 

 olfactory nerves across the orbital cavity, while Lepidotus is 

 paralleled onlr by the last-named genus in the absence of a gular 

 plate. Oil the other hand, the superficial bones of the two extinct 

 genera differ greatlv from those of LepldostMs and cljsely resemble 

 those of Amia-, the peculiar attachment of the premaxilla in 

 Lepidotm, for example, being reproduced almost in detail in the 

 last-named genus. 



EXPLANATION OF THE PLATES. 

 Plate XLIX. 



Fig. L Lej)idotits latifrons, ,><p. nov. ; cranial roof, upp"r a-spa'-t, one lialf n itural 

 size. Oxford Clav ; Peterborough. [B.M., no. P. OSiL] 



CO., cirt'iiuiorbital ; fr., frontal ; pa., parietal ; sq., sqiianusal ; 

 St., supratemporal. 

 1 a, h. Basioccipital, lateral and posterinr aspects. 



a, surface of attachment for lateral bones of cranium ; hr.c., basi- 

 cranial canal; «./, notocliordal fossa; y., .supposed vertebra; 

 .r, lateral )3rocess. 

 1 e. Right premaxilla, showing base of ascending process. 

 1 d. Portion of left mandibular ramus, outer aspect. 



ag., angular; c^., dentary. 

 1 e. Ceratohyal. 



2. Ditto ; right maxilla. Ibid. [B.M., no. P. ()838.] 



3. LejjiihituH minor, Ag.; right premaxilla. Purbeck Formation; Swanage. 



[B.M., no. -tS:J71.] 



4. Lepidotus mantelli, Ag. ; transverse .section of snout. [B.M., no. 



P. 6842.] 



eth., canal through ethmoid bones ; p., palato-pterjgoid arcade ; 

 v., vomer. 



Plate L. 



Fig. 1. Lepidotus lafij'rons. sp. nov. ; opercular apparatus of left side, one half 

 natural size. Oxford Clay; Peterborough. [B.M., no. P. ().S41.] 

 br., branchiostegal ray ; i.op., interoperculum ; op., operculum ; 

 p.op., preoperculum ; s.op., subopcrculum. 



2. Ditto ; hyoraaudibular, one half natural size. Ibid. [B.M., wo. 



P. C840.] 



p., process for operculum. 



3. Dapediux, 6\).; cranium from the lateral, posterior (3 rt), and anterior 



(3 /y) aspects. Lower Lias ; Lyme Regis. [B.M., no. P. 3541.] 

 b.occ, basioccipital ; bc.c, basicraiiial canal ; c, ethmoidal region ; 

 /., foramen for olfactory nerve ; /«., temporal fossa; w./., noto- 

 chordal fossa ; />/.V., parieto-fronto-squamosal shield ; s.occ, 

 supra-occipital. 



4. Dapediiis grantdatus, Ag.; prciuaxilliB {pmx.) and ollnnoidal dermal 



plate {(th.), anterior a.spect. Lower Lias; Lyme Regis. [B.M., 

 no. P. o.")38.] 



B.M. ^British Museum. Unless otherwise stated tlie figures are of liie 

 natural size. 



Puoc. ZooL. Soc— 1803. Xo. XXXVIII. 38 



