Review of Recent Geological Literature. 
49 
tian lakes over Niagara falls from the time of their beginning until the 
re-elevation of the land prevented an outflow east of lake Nipissing. If 
this conclusion shall be sustained by future investigations, the Niagara 
gorge will be accepted as a geologic chronometer of Postglacial time, 
giving for it an approximate measure of 7,000 years, as in 1886 it was 
suggested to be. 
It is also noteworthy that in Mr. Gilbert’s paper the area of the gla¬ 
cial lake Warren, outflowing south westward from lake Michigan at 
Chicago previous to the beginning of the Niagara river, is not regarded 
as including the lake Superior basin. The reviewer here again wishes 
to refer to his papers as just cited for support of the view, advanced 
most notably by Dr. A. C. Lawson, that lake Warren included the pres¬ 
ent lake Superior, reaching, indeed, during its greatest expansion, from 
Duluth to Buffalo and the west part of lake Ontario, thus covering the 
area which later has been so deeply trenched by the Niagara river. 
Glacial lakes, instead of marine submergence, seem to have formed all 
the Late Glacial or Champlain shore lines around the five great Lau¬ 
ren tian lakes. w. u. 
Under sokning dr of ver Zonen rued Agnostus Icevigcitus i Vestergot- 
land. Af Ivar D. Wallerius. (Lund, 1895.) This memoir on the 
fauna of the zone at the top of the Paradoxides beds of Sweden adds 
very considerably to our knowledge of that narrow band of the “ alum 
slates.” G. Lindstrom’s list of the fossil faunas of Sweden, part I, 
published seven years ago, gives ten species of various classes of animals 
as all that were known from this band at that time. The author of 
the present memoir has doubled the number of species, and among the 
genera he describes are some interesting new trilobites. 
Solenopleura (?) stenometopci, whose generic name was left in doubt 
by Angelin, becomes the type of a new genus, AcroceplialUex, charac¬ 
terized by a suture running inward to the rim of the head shield in 
front of the eye, a pointed front to this shield, and a small knob in 
front of the glabella. Proceratopyge , another genus, as the name in¬ 
dicates resembles the typical species of the Ceratopyge zone of Sweden, 
at the top of the Cambrian system ; it differs from Ceratopyge in its 
conical glabella, its four pairs of glabellar furrows, and the triangular 
front fold of the rim. 
A remarkable genus is the minute Toxotis which retains several em¬ 
bryonic or early larval characters, as the narrow glabella and three 
swellings on the front of the shield ; of these the central one holds the 
position of the front lobe of the clavate axial ridge of the protaspis of 
the trilobites.* The two lateral swellings would be in the position of 
the eye-lobes of the protaspis as claimed by Beecher. The pygidium of 
this genus, by its numerous somitic lobes, shows a considerable ad¬ 
vance beyond the embryonic or earliest larval stage of the primordeal 
trilobites. 
*C. E. Beecher: The larval stages of trilobites. Amek. (Ieol., vol. xvi, pp 165- 
197, Sept., 1895. 
