4. Part of the ventral scutellation and ribs of Sauropleura digitata Cope, from the Coal Measures of Linton. Ohio. Original in American Museum of Natural History. × 1.
[CHAPTER XVIII.]
THE MICROSAURIAN FAMILY NYRANIIDÆ, FROM THE COAL MEASURES OF OHIO.
Family NYRANIIDÆ Lydekker, 1890.
Lydekker, Cat. Fossil Reptilia and Amphibia, p. 166, 1890.
Skull with the palatines situated near the middle line, internally to the vomers and pterygoids, and the palatine vacuities small and placed far back. Vertebræ (Ichthyerpeton) discoidal. Teeth less complex than in the Anthracosauridæ. A ventral armor present and the entire body covered with small cycloid imbriated scales.
The type genus of this family was placed by Fritsch ([251]) with the Archegosauridæ, although its resemblance to Anthracosaurus was pointed out; it was subsequently made the type of a family by Lydekker ([393]) in 1890, and placed next the Archegosauridæ. Known from the Coal Measures of Bohemia, Ireland, and Ohio.
Two genera from North America, Ichthyerpeton and Cercariomorphis, are assigned tentatively to this family, both known from the Coal Measures ([462]) of Linton, Ohio, and both with the body completely scaled. The distinguishing characters are found chiefly in the shape and arrangement of the scales, the structure, form, and size of the body, all of which are given full treatment in the discussion below.