88 PISCES CLASsi 



genus ranging upwards to the Lower Cretaceous both in Europe and North 

 America. Fine specimens in the Lithographie Stone of Bavaria and France. 



Mesturus, Wagner.^ Much resembling Gyrodus, but with more irregulär 

 teeth, rounded caudal fin, and scales often united above and below by jagged 

 sutures. M. verrucosus, Wagn., from Lithographie Stone of Bavaria. 31. leedsi, 

 Sm. Woodw., represented by fine specimens displaying osteology from Oxford 

 Clav, Peterborough. 



Stemmatodus, Heckel. Small, resembling Microdon. Vomero-palatine teeth 

 in five, splenial in three rows, all teeth rounded and not very unequal in size. 

 Lower Cretaceous ; Castellamare. 



Coelodus, Heckel. Hinder half of trunk scaleless. Vomero-palatine teeth 

 with one median row of large, transversely elongated, smooth, oval teeth, and 

 two lateral rows of small teeth. One row in the splenial dentition relatively 

 very large, its teeth transversely elongated. Caudal fin either slightly ex- 

 cavated or convex mesially and slightly hollowed laterally^ Lower Cretaceous 

 of Istria, Dalmatia, Southern Italy, and England ; also Cenomanian and 

 Turonian in Europe and North America. 



Anonioeodus, Forir (Fig. 160). Vomero-palatine teeth in three or five 

 longitudinal series, more or less irregulär. Splenial dentition with one row 

 relatively large, the lateral series more or less irregulär, and not reaching the 

 oral border of the bone. A. subclavatus, Ag. sp., from Upper Cretaceous, 

 Maestricht. A. muensteri, Ag. sp., and other species from the European 

 Greensand. Also North America. 



Palaeohalistum, Blv. Upper Cretaceous ; Europe, Asia, and Brazil. Upper 

 Eocene ; Monte Bolca. 



Pycnodus, Ag. Trunk rather elongated, with slender caudal pedicle and 

 forked caudal fin. Dorsal much more extended than the anal fin. Scales 

 thin, absent on the caudal region. Teeth of the three middle rows of the 

 vomero-palatine rounded, those of the two outer rows somewhat smaller and 

 elliptical. P. platessus, Blv. sp., from Upper Eocene ; Monte Bolca. Dentition 

 in the Eocene of several European localities. P. r)iokattamensis, Priem, from 

 Eocene, Mokattam Hills, Egypt. 



Family 7. Aspidorhynchidae. Woodward.'^ 



Very slender, elongated fishes, with enamelled rliomhoid scales of different sizes. 

 Snout beak-like, elongated, and pointed. Maxilla loose ; mandihle with a movable 

 praemandibula {^^ presymphysial bone''). Teeth conical, pointed. Branchiostegal 

 rays numerous. Notochord with ring-vertebrae. Caudal fin externally homocercal. 

 Fin fulcra minute. Bathonian to Upper Cretaceous. 



Aspidorhynchus, Ag. (Fig. 161). Thin, slender fishes, attaining a metre in 

 length, with enamelled ganoid scales, which are yellow or brown in colour, more 

 or less rugose externally, and not remarkably thick. Pectoral fin with very 

 broad rays, which are jointed only in their distal quarter ; no fulcra. Pelvic 

 fin somewhat behind the middle point of the trunk. Anal fin opposed to the 

 small dorsal fin. Caudal fin deeply forked, with delicate fulcra. Lower jaw 

 much shorter than the snout, which is formed by the mesethmoid and pre- 



1 Woodioard, A. S., Ann. Mag. Nat. Hist. ser. 6, vol. XVII. 1896, p. 1. 



'^ Reis, 0., lieber Aspidorhynchus, Belonostomus, und Lepidosteus (Sitzungsb. k. bay. Akad. 

 Wiss., math.-phys. Cl.), 1887. 



