ORDER GANOIDEI. 



971 



one, and a row of small lateral ones on either side. In the cranium 

 the most striking feature is the anterior position of the orbit, which 

 has three large suborbital bones behind it. Other more imperfectly 



Fig. 905. — A mandibular ramus of RJiizodus Heberti; from the Carboniferous of Scotland. 



Reduced. 



known genera of this family from the European Carboniferous are 

 Dendroptychius, Strepsodus, Rhomboptychius, and Archichthys. 



Family Osteolepidid^e (Rhombodipterid^e). — In this family the 

 fins have the same general structure as in the preceding ; but the 

 scales are of the rhomboidal form typical of the order. There are 

 a number of lateral jugular plates ; the teeth are numerous and 

 sharply-pointed ; and the ossification of the vertebral column is 



Fig. 906.— A, Polyfiterus bichir; from the Upper Nile, b, Osteolepis macrohpidotus ; from 

 the Devonian of Russia. (After Pander.) Both figures reduced, a, Pectoral ; b, Pelvic ; c, Anal ; 

 d, d', Dorsal fins. In the lower figure the dorsal fins should be placed more in advance of the 

 pelvic and anal. 



imperfect. The family is divided into two subfamilies ; the first, 

 Osteolepidina (Saurodipterini) being characterised by the smooth 

 scales, and presence of a median jugular plate. The type genus 

 Osteolepis (fig. 906, b) has a long and slender body, with the two 

 dorsals placed respectively in advance of the pelvic and anal fins. 

 The type species is of considerable size. In the allied Thursius, of 



