28 



PISCES 



*S'. hijbodoides, Egert. sp., represented by fin spines and teeth in English, 



Welsh, and Scottish Coal Measures. 



Hyhodus, Ag. {Meristodon, Ag.), (Fig. 51). Teeth and dorsal fin spines 



almost as in SphenacanfJms : but double series of denticles on hinder face of 



fin- spine median, not laterally placed. 

 Symphysial teeth few and relatively 

 large. Notochord persistent, but ver- 

 tebral arches calcified. One or two 

 large hook -shaped, semi -barbed dermal 

 spines (Sphenonchus) immediately behind 



Teeth otMybodus. A, H. pKcatilis, Ag. Muschel- p„f,>, nrbif at Ipntit in thp malp ShaoTPPn 



kalk ; Laineck, near Bayreuth. B, H. reticulatus, eacn OrDlt, aL leaSD in tne maie. K^nagieen 



Ag. Lower Lias ; Lyme Regis, Dorsetshire. CH. sparse, COnsistins; of Small COuical, 



'polypnon, Ag. Lower Oolite (Dogger) ; Stouesfield, ^ \ ?i ^ ■ ^ 



Oxfordshire. radiately grooved tubercles, which are 



sometimes fused into groups of three. 

 Numerous species ranging from the Trias to the Lower Cretaceous. Teeth 

 of H. plicatilis, Ag. (Fig. 51, A), abundant in the Muschelkalk. Nearly 

 complete skeletons from the Lower Lias of England (H. delabechei, Charles- 

 worth ; H. reticulatus, Ag., Fig. 51, ^) and the Upper Lias of Wiirtemberg {H. 

 haujfiamis, Eb. Fraas). Fine skulls from Wealden, Pevensey Baj^, Sussex 

 {H. basanus, Egert.). 



Acrodus, Ag. (Thectodus, Plieninger), (Fig. 52). A genus only dilTering 

 fi'om H//hodus in the rounded, non-cuspidate character of the teeth. Common 



Acrodus aniiinyiae, Ag. Dentition, 1/3 natural size. Lower Lias ; Lyme Regis. 

 -4, .Symijhysis. B, Detached tooth, seen from side and above, natural size. 



in the Triassic and- Jurassic, and ranging to the Upper Cretaceous. A. 

 gaillardoti, Ag., teeth from Bunter, Muschelkalk, and Keuper of Germany 

 and France. A. minimus, Ag., common in European Keuper and Rhaetic. 

 A. anningiae, Ag. (Fig. 52), and A. nobilis, Ag., known by fine specimens from 

 the Lower Lias, Lyme Eegis. A. levis, Sm. Woodw., teeth from English 

 Gault. 



Palaeobates, Meyer. Teeth depressed, rounded, without lateral denticles 

 and not keeled. European Triassic. 



Asteracanthus, Ag. (Sfrophodus, Ag.; Cartodus, Sauvage), (Figs. 53, 54). 

 Principal teeth elongated, irregularly quadrate, with slightly arched but 

 flattened crown ; symphysial teeth few, smaller but relatively large, much 



