Mesozoic and CcBiiozoic Geology and PalcBontology. 153 



Pterozamites gracilis, P. obtu.ncs, P. linearis, P. sjyatulatus, Dioonites 

 linearis, Strangerites planus, Pterophyllum rohustum, Noeggerathia 

 striata, Comephyllum, cristatum, Amhlypterus ornatus, JRahdiolepis 

 speciosus, Jlicrodus la'vis, Pahvonornis striitfiion aides, and Dromath- 

 erium silvestre, the most ancient mammalian remains yet found upon 

 the continent. 



In 1857, T. A. Conrad* described, from the Triassic black shale at 

 Pliffinixville, Pennsylvania, 3fyacites pennsylvanicus. 



In 1858, Meek and Haydenf described, from the Jurassic of the 

 Black Hills, Pentacrinus asteriscus, Lingula brevirostra, Avicula 

 tenuicost'ita, Mytilus pertenuis. Area inornata, now Grammatodon 

 inornatus, Panopoia subelliptica, now Myacites subelliptiGus, Am- 

 monites cordiforniis, A. henry i^ and Belemnites densus. 



Prof, Hitchcock made his report on the Ichnology of New England,^ 

 being " A report on the Sandstone of the Connecticut valley, especially 

 its Fossil Footmarks, made to the government of the Commonwealth of 

 Massachusetts." This work contains a bibliography of North Ameri- 

 can Fossil Footmarks; the histor}^ of the discoveries of the tracks; a 

 discussion of the geological position of the Connecticut river sand- 

 stone, and the evidences tending to prove the Jurassic Age of at least 

 the upper half of the strata, with geological sections across the valley, 

 showing that in general the dip is easterly, varying fron 5° to 50°, 



The sandstone of the Connecticut valley extends from Northfield, 

 in the Northern part of Massachusetts, across the latter State, and 

 Connecticut to Long Island Sound, a distance of 105 miles. The great- 

 est width is at the mouth of the Farmington river, though Hitchcock's 

 Springfield section was taken where the width is nearly as great. 

 Several ranges of trap rock (greenstone, amygdaloid, and volcanic 

 grit), traverse the sandstone longitudinally, having for the most part a 

 northeasterh' trend, and being generally in the form of interstratified 

 beds or masses. Along the west side of the vallej^ there is a coarse, 

 thick-bedded sandstone, whose prevailing color is red, but which is 

 sometimes mottled, and near the trap and the hypozoic rocks, some- 

 times nearly white. This sandstone underlies the trap. Immediately 

 above the trap, on the east side of the valley, the rocks consist of inter- 

 stratified red and black shales, volcanic grit, micaceous sandstone, 

 compact, fetid blue and gray limestone, and in some places coarse sand- 

 stone and conglomerate. It is in the shales and sandstones Iving im- 



'' Proc. Acad. 'NaX. Sci., vol. ix. 

 t Proc. Acad. Nat. Sci. 



