84 BIBLIOGRAPHY AND INDEX OF N. A. GEOLOGY, [bull. 135. 
502 Scudder (Samuel H.). Tertiary Tipulidaj, with special reference 
to those of Florissant, Colo. 
Am. Phil. Soc, Proc, vol. xxxii, pp. 163-245, pis, i-ix. 
Abstracts: Am. Jour. Sci., 3d ser., vol. xlvii, p. 481 (£ p.) ; Am. Nat., 
vol. xxviii, pp. 951-952. 
Gives a historical account and list of the European Tertiary Tipu- 
lidte and description of species from Colorado. 
502a American Tertiary Aphidre. 
Abstract : Am. Nat., vol. xxviii, p. 881 (£ p.). 
Noticed in Bibliography and Index for 1892 and 1893. 
502/> Insect fauna of the Rhode Island coal field. 
Abstract : Am. Geol., vol. xiv, p. 330 (£ p.). 
Noticed in Bibliography and Index for 1892 and 1893. 
503 Seamon (W. H.). The present condition of the earth's interior as 
viewed from the standpoint of the nebular hypothesis. 
Am. Geol., vol. xiv, pp. 20-25. 
Discusses the different theories as to the condition of the interior of 
the earth. 
504 Selwyn (Alfred R. 0.). Volcanic rocks in the Keewatin. 
Science, vol. xxiii, pp. 107-108. 
In a letter to Professor Dana, dated Montreal, December 9, 1879, dis- 
cusses the character of volcanic rocks in pre-Cambrian strata. 
505 Shaler (Nathaniel Southgate). Pleistocene distortions of the 
Atlantic seacoast. 
Geol. Soc. Am., Bull., vol. v, pp. 199-202. 
Abstracts: Am. Jour. Sci., 3d ser., vol. xlvii, p. 138 (1 p.) ; Am. Geol., 
vol. xiii, pp. 143-144. 
Discusses the evidences of orogenic action in Pleistocene time in the 
region of Marthas Vineyard, and the extent, character, and origin of 
the movements. 
506 Relation of mountain growth to formation of continents. 
Geol. Soc. Am., Bull., vol. v, pp. 203-206. 
Abstracts: Am. Jour. Sci., 3d ser., vol. xlvii, pp. 138-139 (f p.); Am. 
Geol., vol. xiii, p. 144 (| p.). 
Describes the limitations as to the positions of mountains, and 
discusses the origin and occurrence of the broad belt of crust which 
supports the arches of strata formed by mountain-building forces, 
and on which the mountains lie in short ridges. Discusses the causes 
of mountain uplifting above sea level. 
507 Phonomena of beach and dune sands. 
Geol. Soc. Am., Bull., vol. v, pp. 207-212. 
Abstracts : Am. Jour. Sci., 3d ser., vol. xlvii, p. 139 (f p.) ; Am. Geol., 
vol. xiii, pp. 144-145 (f p.). 
Discusses the causes of the resistance of beach sands to erosion, and 
describes their action in protecting seacoasts from erosion and their 
source of supply. Describes the resistance of dune sands to the per- 
colation of water and the manner in which the material is transported. 
