548 FOSSIL TURTLES OF NORTH AMERICA. 



the outer ends of the costals (fig. 3 of plate 1 13), the pits arrange themselves more or less in 

 rows parallel with the length of the animal. On an average there are about 8 pits in a line of 

 25 mm. Near the middle line posteriorly some of the pits may have twice the average size, 

 hut this is unusual. Along most parts of the sutural borders of the costals there is a strip 

 which is almost devoid of sculpture, except some striations at right angles with the suture. 

 This condition is most conspicuous on the proximal halves of the costals. 



In a foot-note to the description of his Trionyx leucopotamicus Professor Cope has charac- 

 terized a species, T. punctiger, from the White River beds of Billings County, North Dakota. 

 One of the characters which are given to distinguish the latter from the former is the presence 

 of a pitless band of surface along the sutural borders of the costals. That is present in the 

 specimen which has here been described as Platypeltis leucopotamica, but the writer can not 

 on that account assign it to T. functiger. The latter species is said to have the ridges of the 

 sculpture thickened and irregular and obscure on the outer ends of the costals. That is not 

 true in the carapace above described. T. puncttger is said to have the shell thicker than that of 

 T . leucopotamicus. Cope's type of the latter species has a thickness, thru the rib, of only 

 6 mm. The carapace here described from Nebraska has a thickness thru the ribs varying 

 from 9 mm. to 1 1 mm., which is the thickness in the same regions of T ' . functiger. It appears 

 to the present writer that T. punctiger is identical with T. leucopotamicus; but more materials 

 must be collected before certainty on this point can be obtained. 



It is not known to the writer where the type of T. punctiger is. 



Professor Cope in his description of this species spoke of its close resemblance to Leidy's 

 Tnonyx uintaensis. Now that we have the complete carapaces of both species, it is seen that 

 they are extremely different. 



Platypeltis ferox (Schneider). 



Trionyx ferox, SCHNEIDER, Schildkrote, 1783, p. 330; BOULENGER, Catalogue Chelonians, 1889, p. 259. 

 Platypeltis ferox, AGASSIZ, Contrib. Nat. Hist. U. S., I, pt. ii, 1857, p. 401. 



In the Dr. Jarman collection of fossils obtained in Hillsboro County, Florida, and now the 

 property of the Vanderbilt University, Nashville, Tennessee, there are several fragments of 

 plastral and carapacial bones which the writer can not distinguish satisfactorily from corres- 

 ponding bones of the above species, now living in the rivers of Florida. With these bones come 

 others which evidently belong to 2 or 3 undescribed species of the genus; but the fragments 

 hardly justify the application of systematic names to them. The beds furnishing these bones 

 are supposed to belong to the Peace Creek formation. 



Dr. Friedrich Siebenrock (Sitzber. Acad. Wien, math.-naturw. Cl., cxi, 1902, p. 829) 

 regards this species as identical with P. spinifera. In fact the two forms are very distinct. 

 P. ferox has the carapace much more elongated and the sculpture is much coarser. Their 

 geographical distribution is different also. 



THE END. 



