512 



ZOOLOGY. 



The Ichthyosaurs were colossal reptiles from two to thirteen 

 metres (six to forty feet) in length, swimming in the ocean by 

 four paddle-like limbs consisting of six rows of digital bones 



Fig. 448. Skull of Ichthyosaurus ; lateral view. Pmx, premaxillary bone ; MX, 

 maxillary ; JV, nasal ; Fr, frontal ; Prf, prefrontal ; Pqf, postf rontal ; Pa, parietal 

 L, lachrymal; M, malar; Qj, quadratojugal ; O, quadrate; Fob, postorlntal ; Sq. 

 equamosal ; Z>, dentary ; Ang, angular ; Art, articular ; S. Ar, subarticular ; Pttr 

 pterygoid. After Cope. 



the head was very large, the neck very short, and the orbits 

 were enormous ; the vertebrae were remarkably short and bi- 

 concave. They were carniv- 

 orous, and powerful swim- 

 mers, and common in the Ju- 

 rassic seas of Europe ; one 

 form existed in the Jurassio 

 times in Wyoming. 



Order 7. Theromorpha. 

 This order is divided into the 

 Pelycosauria and Anomo- 

 dontia. The beaked 'Saurians 

 were somewhat lizard-like, but 

 pig. 449.-Posterior view of the skull of were synthetic types, combin- 



Ichthyosaurus ; lettering as in Fig. 443, . , , , , 



with following additions ; Bo, basiocci- mg the characters of the Ich- 



pital ; Exo, Exoccipital ; Sun. 0. supra- , , ,-, , , -, , -, 



occipital ; Opo, opisthotic ; Stan, supra- thyOSaurS, the turtles, the 



stapedialorfiyomandibular.-AAerCop 



,-, 

 the 



wit h those of liz- 



ards, Dinosaurians, and crocodiles. The skull was short, 

 and in Dicynodon the jaws in front had the nipping, horny 

 beak of a turtle, while from behind in the upper jaw pro- 

 truded two long, curved, canine teeth. Dicynodon tigricepx 

 Owen, had a skull about half a metre (20 inches) long. 



