ORDER III URODELA 135 



Measures of Nova Scotia, Pennsylvania, Kansas, and elsewhere. They occur 

 also in the Eothliegendes of Thuringia, Saxony, and Bohemia ; in the Karoo 

 Formation of South Africa, and the Connecticut Valley Trias. More notable 

 still are the Buntsandstein localities in Thuringia (Fig. 228) and Franconia, 

 and those of the English and Franconian Keuper. The impressions always 

 occur along stratification jolanes, and on removal of the superjacent layer the 

 counterpart appears in relief, and is usually accompanied by a series of fossil 

 mud-cracks. Most of these tracks are five-toed, although some/ occur in which 

 the manus, which is invariably of smaller size than the pes, has but four digits. 



Order 2. GYMNOPHIONA. {Apocla, Oppel.) 



Vermiform amphibia covered tuith small scales, arranged in transverse rings, 

 and without limbs. Vertebrae amphicoelons, with persistent notochord. Cranium 

 ossified ; maxillae and palatines with small, backwardly curved teeth. Bibs weakly 

 developed. Pectoral and pelvic arches absent. 



The Coecilians constitute a small group restricted to the South American 

 and Indo-African tropics, and are unknown in the fossil state. 



Order 3. URODELA.^ (Caudata : Batrachia gradientia.) 



Elongate amphibia with naked skin, usually with two pairs of short limbs and 

 ferennial tail, ivith or without external gills. Cranium without supraoccipital, p)0st- 

 orbitals, and supratemporals. Vertebrae usually completely ossified. No parietal 

 foramen. Bio-sacral connection acetabxdar. 



XJrodeles are distinguished from Stegocephalians chiefly by their naked 

 body, solid vertebrae, extremely short ribs, and peculiarities in the conforma- 

 tion of the skull and pectoral arch. The vertebrae may be either amphicoelous 

 or opisthocoelous, are rarely pierced for the notochord, and have weakly 

 developed spinous and transverse processes. 



The skidl, which is broad, flattened, and anteriorly rounded, remains partly 

 cartilaginous even in the adult, and both membrane and cartilage bones are 

 among its components. The cranial roof is formed by the parietal, frontal, 

 and prefrontal elements, adjoining which on either side are the large temporal 

 fossae and orbits. The nasal capsule is sometimes covered by ossified nasals, 

 and sometimes remains cartilaginous. The anterior and lateral margins of 

 the skull are formed by the premaxillae and maxillae, but the latter are 

 sometimes entirely wanting. In the basioccipital region only the exoccipitals 

 are ossified, and the auditory capsule remains either cartilaginous or partially 

 ossified, being covered by a thin, transversely elongated squamosal. Jugal 

 and quadrato-jugal are absent, the quadrate is small, and only its articular 

 extremity is ossified. Parasphenoid, vomers, and pterygoids are conspicuous 

 on the under side of the skull, but the palatines are frequently atrophied. 



1 Meyer, H. von, Zur Fauna der Vorwelt, pt. 2. Frankfort, 1845. — Salamandriuen aus der 

 Braunkoble, etc. (Palaeontogr. vol. VII.), 1860 ; also vol. II. p. 70, and vol. X. p. 292.— Sir audi, 

 A., E,evision der Salamandridengattiingen. St. Petersburg, 1870. — Wiedersheim, R., Salamandrina 

 perspicillata, Versuch einer vergleichenden Anatomie der Salamandrinen. Wurzburg, 1875. — Das 

 Kopfskelet der Urodelen. Leipzic, 1877. — Dollo, L., Note sur le Batracien de Bernissart. (Bull. 

 Mus. Roy. d'Hist. Nat. Belg. vol. III.), 1884. \_Hylaeobatrachus.'] 



