430 



THE GEOLOGIST. 



liosaiirian from the f^oal-formation of jN'ova Seofcia, by Mr. O. C. Marsh, 

 Eeptilian remains from the coal-measures have hitherto been few in nnm- 

 ber, and hare been nearly all regarded as Batrachian or Amphibian. 

 The present remains were embedded in astratumof argilla'jeous chocolate- 

 coloured shale, which forms part of Group XXVI. of the section made of 

 the South Joggins coal-formation, in 1852, by hjell and Dawson, and is 

 about 800 feet above the level of the beds which have furnished the Den- 

 derpeton and Sy'^onomus. These remains are those found in 1855 by 

 Mr" Marsh, and'referred to at page 110 of this journal. 



GrEEAT Ameeican Deseet, — In their acquisitions from Mexico the 

 Americans have acquired not only good, bad, and indifferent lands, but 

 they have also acquired the Great Colorado Desert, extending from the 

 base of San Bernardino south-westwards, for 180 miles, and having a 

 superficial area of 9000 square miles. Excepting the Colorado the 

 whole of that district is without river or lake, and the desert stretches 

 off to the horizon on all sides without a vestige of vegetation or life. Its 

 surface is ashy and parched ; its frame of mountauis rise in rugged 

 pinnacles of brown rock, bare even of soil. Words are unequal to the 

 task of describing its wide expanse, the purity of its air, the silence of its 

 night, the brilliance of the stars which shine over it, the glare of the mid- 

 day sun, and the violence of storms of dust and sand. Parts are even 

 destitute of the latter, and present a surface of smooth, compact, sun- 

 baked clay. Other parts are covered with heaps of sand, in depths of 

 fifty to eighty feet high. jN'ear the mountains along the Colorado is a 

 perfectly fiat terrace paved with pebbles, of nearly uniform size, of por- 

 phyry, jasper, quartz, carnelian, and agate, all rounded by the action 

 of water, and polished till they glisten by the driven sand. The northern 

 part of the desert is thought to be the dry bed of an ancient freshwater 

 lake, the beach lines of which are strongly marked; and probably, at 

 a comparatively recent period, the waters of the Californian Gulf covered 

 all the clay portions of the area, which are still below its level ; and if a 

 channel were cut through the natural embankment of the Colorado these 

 portions, at least, of the desert, would be doubtless again covered. It is 

 even proposed to effect an outflow of the river for the fertilization of this 

 vast arid tract by an artiScial irrigation. 



It is possible that the Colorado district may have been elevated within 

 historic or immediately prehistoric times, as earthquakes still agitate that 

 region ; and in 1852 there were eruptions of mud and hot Avater in the 

 central parts of the valley. 



Fossil Fish in Magnesian Limestone. — There has recently occurred 

 in the Magnesian Limestone at Fulwyll Hill some interesting examples of 

 fossil fish. The specimens belong to three or probably four species of 

 Pal(jeoniscus, and to a single species of Acrolepis. Those of the former 

 genus are by far more common, and nearly all of them belong to one 

 species. Specimens of Acrolepis are exceedingly rare. Three species of 

 Palajoniscus have been described by Mr. J. W. Xirby under the names of 

 P. varians, P. Jafus, and P. Ahhsii. They are all small, the largest not 

 being more than four inches in length. Along with the fish have beea 

 found traces of terrestrial plants. Most of these fossils are found in abed 

 of slaty aiul hnninated limestone, not more than two feet tliick, and only a 

 short distance^ troni tlio b:!se of the " Upper Limestone." The occurrence 

 of fish in this subtlivision is interestinu-. as no remains of higher orga- 

 nization than moUusca had bi\'n previously known, to exist in it : nearly 

 all the vortebrata of the Permian series of the district being confined to 

 the marl-slate near the bottom of the formation. They are. in fact, the 



