13G 



THE EXTINCT BATRACHIA, REPTILIA 



less antero-postcrior extent between the groin and transverse suture than in the species of Ohelone. Its trans- 

 verse extent at the same region is greater, implying a greater closure of the Sternal fontancllo. Tt presents on its 

 outer posterior margin a pit for articulation with the xiphisternal by gomphosis. The hyostemal of the right side 

 is much heavier than the last, and has a bevelled outer anterior face, where it rises steeply to meet the marginal bones 

 of the carapace. Its sutural margin is broken away. The xiphisternal is broken at both ends; it is flat and 

 rather thin. A large part of its inner margin is fitted for articulation with the long hypostcrnal. Its thin outer 

 margin is contracted gently, nearly opposite the middle of the posterior fontanellc. 



There are no distinct dermal sutures crossing these. The nuchal marginal scute is confluent with the first 



vertebral. 



Measurements. 



Length of second marginal, 



" eleventh " 



" camhd 



"Width of second " 



eleventh 

 caudal " 



" sixth, infer, face (average^, 



" last vertebral, 



" an anterior do., 



" episternal, 



" hypostcrnal (longitudinal), 

 Length inner suture episternal, 



" free rib, 

 Width costal hone distally, 

 Length carapace (estimated), 

 Width 



OSTEOPYGIS EMARGINATUS, Cope Sp. Nov. 



Of this species a considerable portion of carapace and plastron were discovered near Barnesboro, and deposited 

 in the; Museum at Rutger's College by the State Geological Survey of New Jersey, under Prof. (loo. II. Cook. 



It is near the 0. platylomus, but differs in the greater width of all the marginal bones in relation to their 

 length, in the greater prolongation of the inner edge of the lower race of the lateral marginals, and in the cylindri- 

 cal ribs and rill pits of the lateral marginals. In the O. platylomus the rib pits air, everywhere alike, entirely flat 

 and longitudinal. 



A vertebral osseous plate is strongly cmarginate anteriorly, as in the last species, but not to more than half the 

 depth; the piece is more elongate, especially the antero-lateral or short sides which enter the greatest width twice, 

 in the platylomus 2§ times. In this specimen it is not crossed by a dermal suture; in the other it is, hence the 

 plates compared are not the same, but, probably arc only adjacent. A costal bone exhibits the head of an anterior rib, 

 which has a strong spongy crest on its anterior margin. The anterior sutural margin converges outwardly towards the 

 posterior margin, which is parallel with the rib axis. On the upper surface the sutures of the plates arc distinct; 

 the anterior vertebral is very divergent, making an angle of 45° with tho median line. The anterior suture of the 

 posterior plate of the two is less divergent. Three junctions of posterior and anterior vertebral scute sutures with 

 the costals, compared with two similar junctions in the O. cmarginatus, show that the former come together at a 

 less angle, and arc therefore more oblique. The anterior marginal scute is, as in Chelone, present and not conflu- 

 ent will, the first vertebra] as in (). platylomus. Both the first and second marginal bones are entirely united with 

 the carapace: in the 0. platylomus but the inner half of the second. The anterior vertebral bone widens within 

 tho margin as in other species, but if is tin; first costal which completes tho consolidation of the carapace anteriorly. 

 Both second and first marginal bones are slightly concave along the outer face; both are convex or piano in tho 

 species before described. 



Ft. 



In. 



Lin. 





2 



10.1 





2 



11.1 





8 



8.7 





1 



1'. 





:i 



9.5 





2 



7.2 





1 



9. 





2 



4. 





2 



2. 





2 



5.5 





2 



4. 





2 



8. 





1 



5. 





2 



11.5 



2 



2 





2 







