692 
5. ‘Great Changes of Level in Mexico, 
and the Inter-Oceanic Connections,’ by J. 
W. Spencer. The geological basement of 
Mexico is a post-Cretaceous base level, out 
of which rise the higher mountains. A deep- 
water formation of Mio-Pliocene age rests 
unconformably upon the Cretaceous. These 
rocks, by their distribution, point to a Plio- 
cene submergence, with ‘canals’ or straits 
connecting the Pacific and Gulf waters. 
This conclusion is further substantiated by 
the similarity of the shallow water faunas 
on the opposite sides of the isthmus, the 
deeper water forms being quite unlike. 
This connection was broken by a recent, 
almost modern, elevation, amounting, in 
some places, to 8,000 feet. 
6. ‘The Origin of the Gorge of the Whirl- 
pool Rapids of Niagara,’ by F. B. Taylor. 
From the falls to the cantilever bridge the ~ 
Niagara gorge is broad. At the latter point 
it suddenly narrows, and the diminished 
width continues to within eighty rods of the 
whirlpool. From here to Lewiston it is 
wide again. The author ascribed the for- 
mation of the broad upper and lower gorges 
to the action of the great cataract carrying 
the entire discharge of the upper lakes. The 
narrow gorge of the whirlpool rapids was 
referred to a smaller cataract, when the 
three upper lakes were draining through the 
Nipissing into the Ottawa. Thus, the 
latter gorge, being cut by a comparatively 
small river, must have required for its for- 
mation a long time, probably not less than 
20,000 to 25,000 years. This considerable 
period must, therefore, be reckoned with in 
estimating post-glacial time. 
7. ‘The Glacial Drainage of the Simcoe 
Area in Ontario,’ by F. B. Taylor. In this 
paper the author gave reasons for believing 
that during a period when the Nipissing - 
outlet was closed, a drainage channel was 
established from Georgian Bay through the 
River Trent. 
8. ‘ Exposures near Detroit of Helderberg 
SCLENCE. 
[N.S. Vou. VI. No. 149. 
Limestone, and Associated Gypsum Salt, 
and Sandstone,’ by W. H. Sherzer. The 
highest rocks exposed in southeastern 
Michigan are Upper Helderberg, nearly or 
quite equivalent to Corniferous. They are 
very pure limestones with chert beds, and 
have a thickness of 100-160 feet. Beneath 
them is a series equivalent to the Water- 
lime, chiefly drab dolomites, sometimes 
oolitic. Some distance below the top of the 
Water-line is intercalated a bed of white 
sand, almost pure quartz, many of whose 
grains show secondary enlargment. Ex- 
tending toa depth of over 2,000 feet beneath 
Detroit is a series of beds of gypsum and 
rock salt, the latter aggregating a thickness 
of five hundred feet in three beds. Thus, 
Detroit possesses, in almost unlimited quan- 
tities, the pure limestone and salt which are 
the raw materials of the soda ash and caus- 
tic soda industry. 
The following papers were read by title : 
9. ‘Notes on the Geology of the Lower 
Peninsula of Michigan,’ by A. C. Lane. 
10. ‘The Nomenclature of the Carbon- 
iferous Formations,’ by R. T. Hill. 
11. ‘Ice-transported Boulders in Coal 
Seams,’ by E. Orton. 
12. ‘Clay Veins Vertically Intersecting 
Coal Measures,’ by W. 8. Gresley. 
C. H. Smyru, JR. 
HAMILTON COLLEGE. 
REGENERATION IN OLIGOCHAETE WORMS. 
Proressor T. H. Morean, of Bryn Mawr, 
has made the following summary of recent 
studies upon regeneration in worms :* 
1. Pieces of the anterior end of Allolo- 
bophora feetida containing less than thirteen 
segments rarely, if ever, regenerate posteri- 
orly, yet such pieces can regenerate very 
quickly anterior segments if these are cut 
off. The result shows that the lack of 
power of the anterior pieces to regenerate 
* Archiv fiir Entwickelungsmechanik, V. Band, 3 
Heft. 
