THE MICROSAURIAN FAMILY MOLGOPHID^E. 151 



The base of the left wing of an orthopterous insect possibly allied to Paolia 

 gnrk'vi Scudder lies between the radius and ulna. The nodule also contains impres- 

 sions of plants, a portion of a frond of a Nenropteris and the impression of one of 

 the Cordaites. Lying next the radius is a slender elongate element which may be a 

 rib or a portion of a metacarpal. If a rib, it indicates that the animal belongs among 

 the Branchiosauria. The fragment is only half as long as the radius and is entirely 

 too obscure to base any conclusions. The other characters of the specimen point 

 quite strongly to its microsaurian affinities. 



The structure of the articular surfaces of the limb bones alone would indicate 

 the microsaurian relationship of Erpetobrachium. It may be provisionally asso- 

 ciated in the family Molgophidae with such forms as Molgophis brevicostatus Cope, 

 Molgophis (Plenrop(yx) clavatiis Cope, and Molgophis macrunis Cope from the Coal 

 Measures of Linton, Ohio. 



MEASUREMENTS OF THE TYPE. 



mm. mm. 



Length of scapula 14 Diameter of shaft . . ... 2 



Distal width 6 Distal width 3 



Proximal diameter 3 Length of radius . . 25 



Length of clavicle (?)'...! 24 Proximal width . . 4 



Length of humerus 25 Diameter of shaft . 3 



Length of ulna 24 Width of distal end .. 4 



Proximal width 4 



Genus PLEUROPTYX Cope, 1875. 



COPE, Geol. Surv. Ohio, II, pt. 11, p. 370, pi. xlii, fig. I ; pi. xliv, fig. 2, 1875. 

 COPE, Proc. Phila. Acad. Nat. Sci., p. 16, 1875. 

 MOODIE, Proc. U. S. Nat. Mus., 37, p. 27, 1909. 



Type: Pleitroptyx clavatus Cope. 



The specimens on which the species of this genus repose do not exhibit crania. 

 The 5, probably 6, specimens which represent them offer various views of the ver- 

 tebral column, and in none is there any trace of ventral or thoracic armature. Limbs 

 can be ascribed to them with probability only. The vertebrae are of moderate 

 length, with well-developed zygapophyses, and a short and not very elevated neu- 

 ral spine in the dorsal region, which is not sculptured in any way. The generic 

 character is seen in the ribs. These are rather short and very stout and support an 

 ala on the posterior or convex border, which expands downwards, and then sud- 

 denly contracts to the shaft. The extremity of the latter is broad and truncate, 

 and includes a medullary cavity, which is only partially fitted with cancellated 

 tissue. 



Pleuroptyx clavatus Cope. 



COPE, Geol. Surv. Ohio, n, pt. II, p. 370, pi. xlii, fig. i; pi. xliv, fig. 2, 1875. 

 COPE, Proc. Phila. Acad. Nat. Sci., p. 16. 1875, 

 MOODIE, Proc. U. S. Nat. Mus., 37, p. 27, 1909. 



Type: Specimen No. 8617 G, American Museum of Natural History. 



Horizon and locality: Linton, Ohio, Coal Measures. 



The general appearance of the species of Pleuroptyx is that of the Molgophis, so 

 far as known, but nothing resembling the peculiar structure of the ribs is seen in 

 any other. There is no assurance that the genus is distinct from Molgophis. 



