548 Scientific Intelligence. 



between the Alps-like Appalachia at the east and the low-lying 

 Cincinnatia at the west, was divided longitudinally by the flat- 

 topped and only moderately high Alleghania. The deepest por- 

 tion of the eastern valley lay close to the foot of Appalachia, 

 whence the surface rose westward almost imperceptibly to the 

 crest of Alleghania. The western valley extended as a plateau 

 with its low line crossing eastern Ohio in a south-southwest direc- 

 tion and deepening southwardly. . . . 



" Each basin had its longitudinal river. That of the east, ris- 

 ing in the present confines of New York, flowed with low gradi- 

 ent for more than 1,000 miles, receiving many tributaries from 

 the bold Appalachia and many, perhaps, unimportant tributaries 

 from the gentle slope at the west. Flowing at first close to Appala- 

 chia, it was pressed constantly westward by alluvial fans and 

 cones, which became confluent and finally were modeled into a 

 vast river plain. The main stream was sluggish and often inter- 

 rupted ; daring high floods, the surface was covered broadly by a 

 sheet of water and the debris from different streams was mingled. 

 The river in the western basin received no debris-laden tributa- 

 ries from east or west, except at the extreme north ; it was more 

 rapid than that in the east and pushed its coarse materials far 

 southward. Progressive overlaps show that subsidence prevailed 

 throughout the basin until the later stages, when it was confined 

 to the contracting area of deposit ; but it was differential and not 

 constant. There were long intervals of slight or no movement 

 during which rivers, reduced to base-level, distributed mostly 

 fine material along their lower reaches. At the close of the 

 Pottsville, the valleys had been filled and Alleghania had become 

 buried ; the whole area of deposit was an irregular marshy plain. 

 But the old drainage systems continued until near the close of 

 the Conemaugh and determined the lines of sea invasion ; they 

 disappeared only with changes in the topography, induced by the 

 forces which were eventually to obliterate the basin. During the 

 whole of the Pennsylvanian, a very great part of the basin was 

 near sea-level. After the close of the Pottsville, few portions of 

 the area of deposition seem to have been more than 300 feet 

 above tide and there is no reason to suppose that any portion was 

 at any time much more than 100 feet below tide " (551-553). c. s. 



2. A synopsis of the Recent and Tertiary freshwater Molhisca 

 of the Calif or nian province, based upon an ontogenetic classifi- 

 cation / by Harold Hannibal. Proc. Malacological Soc, X, 

 Pt. II, pp. 112-166, Pt. Ill, pp. 167-211, pis. v-viii, 1912.— A 

 painstaking and detailed study of the freshwater molluscs in the 

 Californian province. The species have all been studied in the 

 light of both their normal and abnormal environment. The 

 abnormal factor is an unusual amount of mineral salt in solution. 

 Brackish waters or lakes in arid regions cause the development of 

 " malleations, plications, or scalarity among the Gastropods, 

 arcuity and roughening among the Pelecypods, and other devia- 

 tions from the types found under normal circumstances. These 



