784 



HISTORICAL GEOLOGY. 



2. Reptiles. — Sea-Saurians. — The skeleton, in restored form, of Ichthyo- 

 saurus communis is represented, y^ the natural size, in Fig. 1313 ; the head, 



1311-1312. 



1311 





g 



■ssSH^ 







wm^ 



1812 



T%. S., 



_ „ , I ■ii.iiiiwnHMiiinfiiiiniiiiiitilif lu, 



" * „ "ii" "f li « ■■Mh::s«m: I." -s , 

 kill I n I ni 'fiH 'M'lniins'iifmiHiiiiiiiimiEiiii 



f 'nHIillllU IHIIilllllf ■lhl>)»IIII Hl» 



Iff » T . 



mm * 



w 



Ganoids. — Fig. 1311, Dapedius, restored (x ^), Lias; 1311a, scales of same; 1312, Aspidorhyncus (x|), 



Solenhofen. 



reduced to ^, in 1314 ; one of the teeth, natural size, in 1316 ; and a vertebra 

 in 1315. The Fish-like biconcave vertebrae suggested the name of the group, 

 from l)(Qv<i, fish, and o-aSpos, lizard. 



131.3-1318. 



Eeptiles. — Fig. 1313, Iclithj-osaurus communis (x j-^) ; 1314, head, id. (x g'j) ; 1315 a, b, view and section of 

 vertebra, id. (x 4) ; 1316, tooth, id. (x J) ; 1317, Plesiosaurus dohchodelrus (x 5^,) ; 1318 a, b, view and 

 section of vertebra of same. 



Of Ichthyosaurians, 25 species have been described from the British 

 rocks ; and of these, 15 were found in the Lias, and 7 in the Upper Jurassic 

 (Etheridge). 



