2 94 PROSAURIA 



the maxillaries and mandibles are triangular, much worn down 

 in front. The ribs are devoid of uncinate processes. Closely 

 allied but larger is Sauranodon of France, which has lost the 

 upper teeth and uses the sharp margins of the jaws instead. 



Pleurosaurus of Germany and France, about 5 feet in length, 

 is remarkable for the shortness of its still pentadactyle extremities, 

 for its short neck, and very long tail ; — an interesting parallel to 

 what has happened in many genera of recent lizards. 



Splienodon s. Hatteria is the sole surviving member of the 

 whole group of Prosauria, and is represented by one species only, 

 >S'. punctatum,, in New Zealand. As the last living witness of 

 bygone ages this primitive, almost ideally generalised type of 

 reptiles, this " living fossil," deserves a detailed description. 



Total length of very large male specimens up to two feet and 

 a half ; in general appearance like many a stoutly built lizard. 

 The general colour of the skin is dark olive-green with small 

 white or yellowish specks on the sides. A series of slightly 

 erectile spines of yellowish colour extends from the top of the 

 head to the end of the tail, but is interrupted on the neck ; they 

 are cutaneous, covered with a thin sheath of horn. The under 

 surface is covered with numerous scales, arranged in transverse 

 rows ; the rest of the body is rather granular. The tail is thick, 

 slightly compressed laterally. The eye is large, dark brown, with 

 a vertical pupil. 



Those who are satisfied with superficial resemblances still 

 group this creature with the lizards, but it reveals itself as a 

 primitive reptile or Prosaurian by the following characters, every 

 one of which distinguishes it from the lizards : — The temporal 

 region is bridged by three bony arcades. The large vomers, 

 palatines, and pterygoids form a broad bony roof to the mouth ; 

 the large quadrates are firmly fixed by the pterygoids, squamosals, 

 lateral occipital bones, and by the jugal bridge. The vertebrae 

 possess an unbroken series of intercentral wedge-bones. There 

 is an elaborate system of abdominal ribs. The humerus has an 

 entepicondylar foramen, and there is also, in contradistinction to 

 the fossil Rhynchocephalia, an ectepicondylar foramen for the 

 passage of the radial nerve. The carpus still has the primitive 

 number of ten bones, all of which remain separate, including the 

 intermedium. Of soft parts are to be mentioned above all the 

 entire al^sence of external copulatory organs, Splienodon being the 



