172 



KEPTILIA 



CLASS III 



Imesting hones of temporal region forming a single h'oad arcade ; quadrate fixed. 



Fremaxillae not elongated ; pterygoids extensive, meeting along the middle line ; 



narial openings divided. Teeth conical,- thecodont, 

 in Single series along margin of jaws. Vertebrae 

 amphiplatyan ; sacrum composed of two to foiir 

 vertebrae. Cervical ribs articulating only with 

 centra, never with their arches ; dorsal ribs single- 

 headed ; abdominal ribs present between the robust 

 limb girdles ; no ossified sternum. Limbs more 

 or less completely paddle- shaped, pentadactylate. 

 Humerus with entepicondylar foramen, and large 

 conical epiphyses ; digits sometimes with super- 

 numerary phalanges. Dermal armour and sclerotic 

 ring not developed. 



This reptilian order ranges from the Trias 

 to the end of the Mesozoic era. The earlier 

 forms are mostly small amphibious animals 

 with slender, elongated limbs, and the later 

 ones large-sized and completely adapted for 

 a marine existence. 



Family 1. Nothosauridae. 



Fig. 272. 



Lariosaurus halsami, Curioni. Muschel 

 kalk ; Perledo on Lake Como, Lombardy 

 Skeleton, dorsal aspect, i/iq. 



Limbs comparatively slender and elongated, 

 with five digits and normal number of phalanges. 

 Coracoids not much extended along their median 

 Symphysis, and not in contact with interclavicle : 

 scapulae well separated by a clavicular arch. 

 Trias. 



Lariosaurus, Curioni {Macromirosaiirns, 

 Cur.), (Fig. 272). Body lizard-like, 20-90 cm. 

 long, tail forming about one-third the total 

 length. There are about twenty cervicals, 

 twenty-four to twenty-six dorsals, four sacrals, 

 and over forty caudals. Cervical ribs small 

 and double-headed ; dorsal ribs very robust, 

 and borne directly by the neural arches. A median longitudinal and two 



the Plesiosaurian Reptilia (Pi-oc. Amer. Phil. Soc. vol. XXXIII. p. 110), 1894. — />«?«<?«, W., 

 (Abhaudl. preuss. Akad. Wiss. p. 1), 1895. — Deecke, W., Ueber Lariosaurus, etc. (Zeitschr. deutsch, 

 geol. Ges. vol. XXXVIII. p. 170), \^%Q.—HawMns, T., Memoirs on Jchthyosauri and Plesiosaiiri. 

 London, \%M.—Hulke, J. W., Anniversary Address (Quar. Journ. Geol. Soc. vol. XXIX.), 1893. 

 Also Proc. Roy. Soc. vol. LI. (1892). — Hiixley, T. //., On Plesiosaurus, etc. (Quar. Journ. Geol. Soc. 

 vol. XIV. p. 281), 1858. — Knight, W. C, Some new Jiirassic Vertebrates from Wyoming (Amer. 

 Journ. Sei. [4], vol. V. p. 378), 1898. Also ibid. vol. X. (1900), p. Wh.— Meyer. H. von, Zur Fauna 

 der Vorwelt, pt. II. Frankfort, 184:7 .—Owen , jR., Monograph of the fossil Reptilia of the Liassic 

 Formations, pt. III. (Palaeontogr. Soc), 1865. Also Geol. Mag. vol. VII. (1870), p. 49 ; and Quar. 

 Journ. Geol. Soc. vol. XXXIX. (1883), p. ISS.Seeley, H. G., The nature of the Shoulder girdle and 

 clavicular arch in Sauropterygia (Proc, Roy. Soc. vols. LI. p. 119, and LIV. p. 160), 1892-93. Also 

 various articles in Ann. Mag. Nat. Hist. [3], vol. XV. (1865), pp. 49, 232 ; vol. XVI. (1865), p. 352 ; 

 [4], vol. VIII. (1871) ; Quar. Journ. Geol. Soc. vol. XXX. (1874), pp. 197, 436 ; vol. XXXIII. 

 (1877), p. 541 ; vol. XXXVIII. (1882). p. 350 ; Ann. Rep. Yorks. Phil. Soc. (1895), p. 2Q.—SoUas, 

 W. F., On Plesiosaurus conybearei (Quar. Journ. Geol. Soc. vol. XXXVII. p. 440), 1881.— 

 Williston, S. W., A new Plesiosaur, etc. (Trans. Kansas Acad. Sei.), 1890. 



