CHAPTER IX. 



THE AMERICAN COAL MEASURES BRANCHIOSAURID^E. 



Definition of the Family Branchiosaurid^ Pritsch, 1879. Coal Measures and 

 Permian of North America and Europe. 



Fritsch, Fauna der Gaskohle, Bd. I, p. 69, fig. 30, 1879. 



Lydekker, Cat. Fossil Reptilia and Amphibia, pt. iv, p. 210, 1890 (Protritonidae). 



Stegocephalic, salamander-like animals, with broad, anteriorly truncate skull. 

 Teeth smooth with large pulp-cavity. The parasphenoid narrowed anteriorly, pos- 

 teriorly expanded to a shield-shaped plate. Vertebrae with the notochord persistent 

 and intra vertebrally expanded. Pelvis well developed, the ilium and ischium osse- 

 ous with large cartilaginous margins, the pubis unknown, possibly hyaline cartilage. 

 Ribs short, straight, present on almost all vertebras. Skin with deUcately ornamented 

 scales. Eyes with sclerotic plates. Palatal elements toothless or with small tooth- 

 hke tubercles on pterygoids and palatines. Ventral armature on throat, chest, and 

 abdomen, extending on to the limbs, consisting of small delicate scutellas arranged 

 in a chevron pattern. 



The above definition is modified from Fritsch (Fauna der Gaskohle, Bd. I, p. 69, 

 1879). 



The North American species are: (?) Sparodus sp. indet. Dawson, Micrerpeton 

 caudatum Moodie, Mazonerpeton longicaudatum Moodie, Mazonerpeton costatum 

 Moodie, Eumicrerpeton parvum Moodie. 



Genus MICRERPETON Moodie. 

 Moodie, Jour. Geol , 17, p. 39, figs, i to 6, 1909. 



Type Micrerpeton caudatum Moodie. 



The genus Micrerpeton, of which the single species is described below, was the 

 first evidence of the occurrence of the Branchiosauria in America. There have been 

 three other genera referred to the Branchiosauria from North American deposits, 

 but there is good evidence that none of them belong there. The genus Amphibamus 

 was originally referred to the Xenorhachia by Cope (105, pp. 134-137) on account of 

 the supposed cartilaginous condition of the vertebra and the absence of ribs. Later 

 he abandoned this order and placed the form in the Branchiosauria, where it was 

 retained by Zittel (642). Recently Hay has shown (316), and I am able to corrob- 

 orate his statement, that ribs are present in the species, and that they are long and 

 curved, not at all like the short ribs of the true Branchiosauria. These long, curved 

 ribs undoubtedly exclude Amphibamus from the Branchiosauria and indicate its 

 close affinities with the Microsauria. The genus Pelion has also been referred to this 

 order on purely negative evidence (642, p. 375). This genus is excluded from the 

 Branchiosauria by the well-ossified condition of the limb bones, in which the endo- 

 chondral ossification is seen to be well developed, a condition not found, so far, 

 among the true Branchiosauria. The form of the head and the elongate hind limb 

 would also tend to exclude the genus from the Branchiosauria. In the Branchiosauria 



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