1893.] OSTEOLOGY OF LEPIDOTrS A^'D D.IPEDIUS. 565 



border of the cranium ; but Daped'ms at least is distinguishad from 

 Amin and approximated to Lepidosteus by the course of the 

 olfactory nerves across the orbital cavity, while Lepidotus is 

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

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

 genera differ greatlv from those of Lepklosteiis aud closely resemble 

 those of Amia ; the peculiar attachment of the premaxilla in 

 Lepidotus, for example, being reproduced almost in detail in tlie 

 last-named genus. 



EXPLAJVATION OF THE PLATES. 

 Plate XLIX. 



Fig. 1. Lepidotus latifrona, sp. nov. ; cranial roof, upper aspeftt, one half natural 

 size. Oxford Clay; Peterborough. [B.M., no. P. 6841.] 



CO., circumorbital ; fr., froutal ; pa., parietal ; sj., Bqu:iina3al ; 

 St., su prate raporal. 

 1 a, b. Basioccipital, lateral and posterior aspects. 



a, surface of attachment for lateral bone.s of cranium ; /c-.e., basi- 

 cranial canal; «./, notochordal fossa; i'., supposed vertebra; 

 X, lateral process. 

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

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



Off., angular; c?., dentary. 

 1 e. Ceratohyal. 



2. Ditto ; right maxilla. Ibid. [B.M., no. P. fi838.] 



3. Lepidotus minor, Aa.; right premaxilla. Purbeck Formation; Swanage. 



[B.IL, no. 48371.] 



4. Lepidotus 7nantelli, Ag. ; transverse section of snout. [B.M., no. 



P. 6342.] 



eth., canal through ethmoid bones ; ;)., palato-pterygoid arcade ; 

 v., vomer. 



Pl.^te L. 



Fig. 1. Lepidotus latifrons, sp. nov. ; opercular apparatus of left side, one half 

 natural size. Oxford Clay ; Peterborough. [B.M., no. P. 6841.] 

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

 p.op., preoperculum ; .i.op., suboperculum. 



2. Ditto; hyomandibular, one half natural size. Ibid. [B.M., no. 



P. 6840.] 



p., process for operculum. 



3. Dapedius, sp. ; cranium from the lateral, posterior (3 rt), and anterior 



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

 b.occ, basioccipital ; bc.c., basicranial canal ; e., ethmoidal region ; 

 /., foramen for olfactory nerve ; m., temporal fossa ; n.f., noto- 

 chordal fossa ; pfs., parieto-fronto-squamosal shield ; s.occ, 

 supra-occipital. 



4. Dapedius ffranulatiis, Ag. ; premaxillse (pmx.) and ethmoidal dermal 



plate (eth.), anterior aspect. Lower Lias; Lyme Regis. [B.M., 

 no. P. 3538.] 



B.M.= British Museum. Unless otherwise stated the figures are of the 

 natural size. 



Piioc. ZooL. Soc— 1893, No. XXX Vm. 38 



