

CRETACEOUS AND TERTIARY—BAD LANDS. 105 
and nearly white indurated clay, in which the most delicate structures 
are perfectly preserved. From its soft and crumbling character, it is 
almost impossible to obtain or keep good specimens ; but, in the frag- 
ments which were preserved, a few very interesting plants appear. Of 
these, some are characteristic of the Fort Union group, and identical with 
those of Porcupine Creek. The association of remains is that of a fresh- 
water pond or lake, anda fine new species of Lemna occurs abundantly. 
254. In the lower portion of this division, the beds are more 
sombre in tint, and little differentiated by colour, which elsewhere 
often renders the stratification apparent. They contain some layers 
of sand and sandstone, which show much false-bedding and current 
structure, and sometimes terminate suddenly with abrupt undulations. 
In some places, sufficient calcareous cement has been introduced among 
the grains to form hard sandstones, but their thickness is never 
great, nor do they extend far. Much ironstone occurs in thin nodular 
layers, and some selenite. About one-third from the base of this division 
a bed was found, in which curious fruits have been preserved, referable 
to a new species of 4#sculus. (Plate XVI., Figs. 8 and 9.) 
255. The most interesting feature of this part of the section, 
however, is the occurrence of the remains of vertebrate animals. They 
are found exclusively in the lower portion of this division, and most of 
them below the fruit-bed just mentioned. They are generally closely 
connected with the ironstone layers, and are often themselves impregna- 
ted with that substance. They are also, unfortunately, apt to be attached 
to the ironstone nodules, or incorporated with them, and traversed by 
crack-lines, in such a way as to render it difficult to obtain good 
specimens. A more prolonged search among these hills, than I was able 
to make, would, however, no doubt result in the discovery of localities 
where the remains are more abundant and in better preservation. 
256. Professor Cope has kindly examined the vertebrate fossils 
obtained in connection with the expedition. Those from this place 
include fragments of severel, species of turtles, scales of a gar-pike, and 
broken bones of dinosaurian reptiles. Of the turtles, two are new 
species, to which Professor Cope has given the names—Plastomenus 
costatus, and P. coalescens—and there are portions of species of Trionyx 
and Compsemys. The gar-pike belongs to the genus Clastes, and of the 
dinosaurian remains, though mostly too fragmentary for determination, a 
caudal vertebra resembles that of Hadrosaurus. 
257. Division y., the lower series of yellow sands and arenaceous 
