MisceUaneoua. 455 



Prof, Ilifchcock .states that it appears to be the impression of a 

 short stiff tail. The present specimen shows clearly that it was 

 made by the obtuse extremities of the ischia. The saurian squatted 

 down, resting on its styloid ischia as the third leg of a tripod, of 

 ■which the anterior pair was represented Vjy the hinder legs. Prof. 

 0. C. Marsh informs me that in the museum of Yale College a slab 

 exhil)iting impressions similar to the above shows the impressions 

 of the anterior feet also, which were put to the ground in the act of 

 rising or sitting, or perhaps reached to it while the animal was 

 squatting, as do those of carnivorous Mammalia. 



The tracks of many of the animals discovered by Hitchcock arc 

 plantigrade. That they could not have walked like the plantigrade 

 mammal is sufhciently evident from the length of the metatarsal 

 elements, which would necessitate a constant contraction of the 

 tibialis anticus muscle, or a peculiar arrangement of the tarsal bones 

 for its support. The latter docs not appear to have existed ; and the 

 former is so very improbable that, in connexion with the pneumatic 

 structure of the bones, there is abundant reason to suppose that thej 

 progressed by leaps, and assumed the plantigrade position when at 

 rest. 



Xo portion of the cranium or dentition of this genus has been 

 preserved. The large stout hooked claws of the fore foot would 

 indicate a more or less carnivorous diet. 



The existence of Symphypoda in the strata here indicated, with 

 the occurrence of a Pterosaurian in a similar situation in Pennsyl- 

 vania, points to the existence of the transition from Keuper to Lias 

 (that is, frcm Triassic to Jurassic beds) in the red sandstones of the 

 eastern United States. They have been heretofore regarded as 

 Triassic*, which the lower portions of them undoubtedly are, and 

 similar to the German Keuper in the presence of Labyrinthodonts, 

 Thecodonts, and Dinosauria in both Pennsylvania and X. Carolina. 



The remains here described were alluded to by Prof. P. Owen as 

 those of a Saurian pointing to the Pterodactyles or Birds, provided the 

 cavities of the bones were filled with marrow, and not with cartilage. 

 Prof. Wyman regarded them as those of a reptile, though the long 

 bones might have been referred to a bird, if considered alone. 

 " "While the bones from Spiingfield are as hollow as those of the Ptcro- 

 dactjle, I do not find that they are those of this animal ; there is 

 no jtositive proof of the long fingers, nor of the broad sternum, which 

 these reptiles possessed. The existence of the large tee in company 

 with the small ene is in favour of a jumping animal." — From the 

 Mctnoir of Prof. Cope on Eatinct I?ei>tilia and AvfS, Anur. Phil. Soc, 

 ttnj}t<blished vohime. — SiUimans American Journal, May 1870. 



• TTitchcock, in his ' Tcbnolog^i- ' ( 18o8\ holds that the beds containing 

 the trrcks are I ower Jurassic, either Oolitic or Lias: ar.d L'ana, in his 

 'Geology' (pp. 414, 448), says that the so-called Tiiassic is probably in 

 part Jurassic. — Ens. Am. Joubx. Sci. 



