212 EEPTILIA class in 



lateral ones triangular, and antorbital opening long and narrow. External 

 nares small ; interclavicle blade-like ; dorsal scutes coarsely sculptured. Elgin 

 Trias ; Scotland. 



Sub-Order 3. MESOSUCHIA. Huxley.^ 



Snout greathj elongated in the earlier forms, short and broad in some of the later. 

 External nares unpaired and terminal ; internal nares confluent, opening at posterior 

 margin of the secondary palate formed by plates of the maxillae and palatines, there 

 being no outgrowths from the pterygoids. Eustachian passages open grooves on the 

 basisphenoid. Parietal and frontal unpaired. Vertebrae amphicoelous, or mwe 

 rarely amphiplatyan. Clavicidar elements wanting. Coracoid elongated, with . slight 

 perforation. Pubis excluded from acetabidum, and borne on an anterior process of the 

 ischium. Anterior extremities pentadactylate ; fifth digit of pes rudimentary. 



The Mesosuchia, which comprise all the Jurassic and a few Lower Creta- 

 ceous crocodiles, were separated by Huxley from the later Eusuchia chiefly on 

 account of differences in the palate, eustachian passages, and vertebral centra. 

 In the present group the pterygoids do not develop secondary plates to 

 prolong the canal of the .nares, which opens at the hinder margin of the 

 palatines ; the eustachian canals are not closed ; and the vertebrae in all but 

 the latest forms are amphicoelous. Like the typical Cretaceous and modern 

 families, the Mesosuchia comprise both long-snouted and broad-snouted croco- 

 diles, the latter, however, not appearing until the Purbeckian. All except the 

 latest forms are adapted for an exclusively aquatic life, and are known from 

 Europe, Madagascar, Patagonia, and perhaps North America. 



Section 1. Longirostres. Lydekker. 



Snout greatly produced. Nasals, as a rule, not reaching the premaxillae and 

 external nostril. Mandibular rami united in a long symphysis fanned by the dentary 

 and splenial. Vertebrae amphicoelous. 



Family 1. Teleosauridae. Zittel. • 



Teeth conical, slender, closely set. Orbits entirely enclosed, superiorly or more 

 rarely laterally directed, and notably smaller than the subrectangular supraternporal 

 vacuities. Prefrontcds small, lachrymals well developed. Antorbital vacuities small, 

 laterally placed. Anterior limb only about half as long as the hinder pair. Dorsal 

 armour consisting of a paired series of broad, overlapping plates; ventral plates 

 suturally united, forming several more or less irregidar series, or a mosaic of small 

 polygonal scutes. Jura. 



^ Literature : 



d' Alton, M., and Burmeister, II., Der fcssile Gaviale von Boll. Halle, 1854. — Bronu, H. G., 

 aud Kaup, J. J., Ueber die gavialartigen Reptilien der Liasformation. Stuttgart, 1841. — Dollo, L., 

 Premiere note sur les Croeodilien.s de Bernissart (Bull. Mas. Roy. d'Hist. Nat. Belg. vol. II. p. 309), 

 1883. — Deslongchamps, E. E., Notes paleontologiques. Caen and Paris, 1863-69. — Le Jura Nor- 

 mand. Caen and Paris, 1877-78. — Deslong champs, J. A. E., Memoir sur les Teleosauriens de 

 I'epoque I'urassique (Mem. Soc. Linn. Norm. vol. XIII.), 1863. — Fraas, E.. Die Meerkrokodile 

 (Wiirtt. iiaturw. Jahresli., vol. LVII. p. 409), 1901.— Pal aeoutogr. vol. XLIX. pp. 1-72, 1902.— 

 Hulke, .T. II'., Skeletal Anatomy of the Mesosuchia (Proc. Zool. Soc. London, \}t. 4), 1888. — 

 Koken, E., Thoracosaurus macrorhynchus Bl., aus der Tutfkreide von Maestricht (Zeitschr. deutsch. 

 geol. Ges. vol. XL. p. 754), 1888. — Lortet, L., Les Reptiles fossiles du Bassin du Rhone (Arcli. 

 Mas. d'Hist. Nat. Lyon, vol. V.), 1892. — Snavage, E., Memoir sur les Dinosaurs et les Crocodilien.s 

 des terrains jurassiques de Boulogne-sur-Mer (Mem. Soc. Geol. France [2], vol. X.), 1874. — Winckler, 

 T. C, Etude sur le genre Mystriosaurus (Arch. Mus. Tylere, vol. IV. pt. 1), 1876. 



