262 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



Lepklocyclhia, including a new subgenus, 31uUicyclina. It also includes 

 the genera Orthophragmina, Nummulites, and OrbitoUtes, and a new 

 genus, Heterosteginoides. Several new species are described. There can 

 be no doubt as to the value of these larger forms as Zone fossils, but in 

 our opinion the constant multiplication of species in these genera is to be 

 deplored. Like the Niimmulites they are fast becoming a highly over- 

 specialized branch of Micro-palaeontology. H.-A. & E. 



Miscellanea. 



The Rounding of Grains of Sand by Solution. — J. J. Galloway 

 contributes to the American Journal of Science (Ser. 4, vol. xlvii, 1919^ 

 pp. 270-80) a very interesting paper upon this subject. He is aware of 

 the experiments of Daubree in this connexion, and the results of his 

 own experiments — i.e. that it requires 800 hours of rolling in water at 

 four miles an hour to produce a round from an angular grain of sand — 

 are practically identical with those of Daubree, who put it at 3000 miles. 

 The author is, however, of opinion that rounded sand-grains are not, as 

 has been generally accepted, necessarily aeolian, but, below a certain 

 diameter, which he puts at 0"1 mm., are produced by solution. He 

 seeks to prove this by experiments with various minerals in alkaline 

 and acid solutions, but his experiments with quartz-sand do not appear 

 to us to be so conclusive. He says himself, " Quartz can be dissolved in 

 a few hours in hot water under pressure. The temperature and pressure 

 of water in which sands are accumulated, however, are not high enough 

 to be important factors in solution." But his observations seem to 

 throw light upon the highly polished or frosted spherules of silica 

 with which one is familiar in examining dredgings from considerable 

 depths. And the solution theory may help to explain the disappearance 

 of flini which forms so large a constituent of the shore sand in some 

 localities, but is absent from dredgings but a short distance away. His 

 conclusion is that while a sand consisting wholly of well-rounded grains. 

 many of which are less than 0' 1 mm. in diameter is aeolian, the presence- 

 of a small percentage of minute round grains points rather to water- 

 action and solution. H.-A. & E. 



