ORDER II 



SQUAMATA 



163 



lignites of Kott, near Bonn ; and the freshwater strata of Steinheim, Haslach, 

 Gtinzburg, Sansan, and Colorado. The most gigantic of all lizards are 



Fi<;. 255. 



(.') Proigvana, sp. Phos- 

 phorite of Quercy. Inner am I 

 outer aspect of dentary, i/i- 



Pig. 256. 



Plestiodo n rait u rce a sis, 

 Filhol. Phosphorite of 

 Quercy. Inner aspect of 

 dentary, Vi- 



Fig. 257. 



Palaeovaranus caylvxi, Filhol. Phos- 

 phorite of Quercy. Maxillary frag- 

 ment, Vi- 



Megalania and Notiosaurus, from* the Pleistocene river deposits of Queensland. 

 The former is estimated to have been about 10 m. in length, and belongs to 

 the Varanidae. 



Sub-Order 4. OPHIDIA. Snakes. 1 



Body serpentiform, without limbs, covered with corneous scales. Vertebrae 

 procoelous, with zygosphene-zygantrum articulation, and the anterior centra with 

 strong simple hypapophyses. Both upper and lower temporal arcades, columella, 

 sacrum, sternum, pectoral arch, abdominal ribs and haemapophyses are wanting. 

 Parietal unpaired, without foramen, the sides extended downward and fused 

 with the prootic, alisphenoid, and orbitosphenoid. Anterior portion of brain case 

 completely ossified. Quadrate and pterygoid movably attached to skull by ligament. 

 Maxillae and palatines usually freely movable, always displaceable. Premaxillae 

 much reduced; mandibular symphysis ligamentous. 



Snakes are chiefty conspicuous for the absence of limbs. The body is 

 greatly elongated, and the number of vertebrae very considerable, sometimes 

 exceeding 400. The centra are concave in front and 

 convex behind, the connection being by free ball-and- 

 socket joints ; and their • articulation is further 

 strengthened by zygapophyses and a zygosphene- 

 zygantrum arrangement. The neural arches are 

 thoroughly coossified with their centra. Simple 

 hypapophyses are developed by the anterior ver- 

 tebrae as far as sometimes the thirtieth, and the 

 transverse processes are short and tumid (Fig. 258). 

 Ribs are almost always present in the trunk region, 

 beginning with the third vertebra ; and being freely 

 articulated, are able to assist in propelling the body. 

 They are long, curved, and frequently hollow • in the 

 caudal region they are replaced by elongate trans- 

 verse processes. Haemapophyses are wanting among 

 snakes, and in their stead occur stout descending branches of the transverse 

 processes (Fig. 259). 



1 Literature : 



Cope, E. D., The Vertebrata of the Tertiary Formations of the West (Kept. U. S. Geol. Surv. 

 Territ. vol. III.), 1883.— Filhol, II., Ann. Sci. Geol. vol. VIII. (1887). p. 27 '0.— Fischer, G., De 

 serpentibus quibusdam fossilibus dissertatio. Bonn, 1857. — Meyer, II. von, Coluber atavus aus 

 dem Siebengebirge (Palaeontogr. vol. VII.), 1860. — Rochebrune, A. F. de, Revision des Ophidiens 

 fossiles (Nouv. Arch. Musee d'Hist. Nat. Paris [2], vol. III.), 1880.— Roemer, F., Ueber Python 

 euboeieus (Zeitscbr. deutseb. geol. Ges. vol. XXII.), 1870. 





Python bivittatus, Schn. 

 Recent: Sumatra. Anterior 

 cervical vertebrae, i/i- ("r Atlas ; 

 \xis ; hyp, Hypapophysis ; 

 r, Rib; sp, Neural spine), (after 

 d'Alton.) 



