60 0. C. Marsh— New Belodont Reptile. 



as the armor was here turned slightly to the right and some- 

 what twisted. This median ridge was formed by the matrix 

 filling the narrow space between the ends of the dorsal plates, 

 where they met in pairs on the median line. The transverse 

 ridges are likewise due to the filling in of the matrix between 

 the adjoining plates, which evidently were somewhat sepa- 

 rated by connecting tissue admitting of more or less motion, 

 but which held the whole dorsal armor together as a carapace. 



The large median plates indicated in this fossil are twenty 

 in number in each of the two rows meeting on the middle 

 line. These plates are elongated transversely, strongly con- 

 vjex, and their form is accurately shown in the figure. Their 

 inner extremities are nearly at right angles to the sides, but 

 the outer ends are oblique where they join the plates of the 

 lateral series, or second row. These lateral plates were quite 

 short, and their form and position are clearly preserved in the 

 specimen figured. All the dermal armor indicated resembles, 

 in its general features, the corresponding portions in the genus 

 Aetosaurus^ Fraas, from the upper Trias of Germany. In the 

 latter, however, the plates are imbricate. 



The above description is based upon the impfessions left by 

 the inferior side of the plates uj)on the plastic matrix in which 

 they were imbedded. The plates themselves have since disap- 

 peared, having been dissolved by infiltrating waters. The cast 

 of the superior surface of the plates was of somewhat softer 

 material than the matrix below, and most of it was lost in 

 removing the specimen. The portions recovered show that 

 the upper surface of the plates was rugose, but not deeply 

 sculptured, being less marked in this respect than in the other 

 known species of Belodonts. The rough surface preserved 

 shows no regular pattern of ornamentation, and there are no 

 indications of a crest on the plates. The form and position of 

 the plates are characteristic features, and as both the genus and 

 species appear to be distinct, the reptile may be known as 

 Stegomus arouatus. The animal when alive was of moderate 

 size, probably eight or ten feet long. This would be about 

 two-thirds the size of Belodon validus^ the scapula of which is 

 eight and one-half inches in length. The fossil here described 

 indicates an animal with a body capable of some lateral flexure 

 and considerable vertical movement. The type specimen was 

 found by F. P. Clark, and presented by D. A. Yan Hise to the 

 Yale University museum. 



Outside the Connecticut valley, remains of Belodontia have 

 been found at several points in this country. Some of the 

 best known were discovered by Prof. Emmons in the Triassic 

 of North Carolina, most of the specimens having been obtained 

 in the Deep river coal mines. One of these fossils is the 

 skull figured by him under the name Rutiodon Carolinensis.^ 

 * Manual of Geology, p. 179, 1860. 



