5H 



FOSSIL TURTLES OF NORTH AMERICA. 



The sculpture of this species is peculiar. It consists of rather large pits of quite regular 

 size and form. They are rather deep, and from the bottom of each the surface rises gradually 

 to the top of the wall surrounding them, thus being bowl-shaped. In A. prisca (Leidy) and 

 some other species, the wall around the pit is more abrupt. Usually three pits occupy a line of 

 15 mm. On the small portion of the plastron referred to, the pits are only about half as large 

 as those of the carapace, and are much shallower. 



Among the fragments supposed to belong to this species is one which seems to have formed 

 a portion of the nuchal. If this identification is correct, this bone was rather thin where it 

 joined the first neural and first costals, but very thick, 1 1 mm., near the anterior border. The 

 free border was rounded in transverse section. At the midline this bone was only about 22 mm. 

 wide fore and aft, but it widened rapidly, being 38 mm. wide at a distance of about 40 mm. 

 from the midline. Thus the carapace appears to have been deeply and broadly excavated in 

 front. There is present a piece of some portion of the plastron. It is probably the bone which 

 Cope regarded as a part of the xiphiplastron. It has a thickness of 13 mm. 



There is in the Philadelphia Academy's collection a fragment of a costal plate which is to 

 be referred to this species. It was found at Camden, New Jersey. This fragment is 38 mm. 

 wide and represents about half the width of the costal. The thickness at the sutural border 

 is 10 mm.; thru the ridge formed by the rib, 12 mm. There are 4 pits in a line 20 mm. long. 



Cope thought that this and some of the other species of Trionychidae were inhabitants 

 of the sea, and he refers to a statement of Du Chaillu to the effect that Amyda tnunguis had 

 been found at sea. The fact may be mentioned that there is in the American Museum of 

 Natural History a specimen of Amyda sinensis (Wiegm.) which was captured in 1902, by Mr. 

 N. G. Buxton in Vladovostock Harbor, Siberia. 



Amyda? pennata (Cope). 

 Plate 96, fig. 6. 



Trionyx pennatus, COPE, Proc. Acad. Nat. Sci. Phila. 1869, p. 12; Cook's Report on Geol. New Jersey, 

 Append. B, 1868 (1869), p. 734; Trans. Amer. Philos. Soc., xiv, 1869, pp. 151, 152, plate vii, fig. 

 13. HAY, Bibliog. and Cat. Foss. Vert. N. A., 1902, p. 454. 



As in the case of too many of our fossil tortoises, our knowledge of this species is meager. 

 The species was based on a portion of the distal end of a costal bone, which was found in the 

 upper, or Eocene, bed of greensand, probably near Squankum, Monmouth County, New 

 Jersey, by Mr. O. B. Kinne. The specimen is now a part of the Cope collection of reptiles 

 in the American Museum of Natural History, and bears the number 1165. Cope, as cited, 

 figured the type half the natural size. On plate 96, fig. 6, of the present work, it is repre- 

 sented of the natural size. 



The fragment is supposed to include a little more than two-thirds the width of the distal 

 end of the costal, unless the rib lay nearer one sutural border than to the other. The costal 

 had, therefore, probably a width of about 60 mm. On the left of the bone, 47 mm. of the 

 sutural border is shown. At the proximal end of this border, the thickness is 7 mm. At the 

 distal end it is IO mm. Where the rib left the costal plate, the thickness is 13 mm. The free 

 border of the costal is cut off at a right angle with the upper surface. 



The sculpture is of a coarse pattern. The ridges are broad and rounded, but the diameter 

 is usually less than that of the intervening furrows. In the type, the ridges run from the sutural 

 border of the bone inward and somewhat toward the distal end, and this arrangement evidently 

 suggested the name pennatus. Soon there appear connecting ridges and the furrows become 

 broken up into large and small pits. Near the border there are 2 furrows in 10 mm. Many of 

 the pits in the median portion of the costal are of less diameter than the surrounding walls. 



Besides the type, there is now in the American Museum a fragment of a costal, No. 2221, 

 which belongs to this species. The bone shows 67 mm. of one sutural border and 8 mm. of the 

 one opposite. The width of the bone was 44 mm. The thickness of the sutural border at one 

 end is 7 mm.; at the other, 9 mm.; thru the rib, 12 mm. In this fragment the principal 

 ridges of the ornamentation run at nearly right angles with the sutural borders, while the pits 

 are very irregular in form and size. 



At what locality this specimen was collected there is no information; but it is very cer- 

 tain that it was obtained in the greensand of New Jersey. 



