878 The American Naturalist, [October, 
GEOLOGY AND PALEONTOLOGY. 
Origin of the Trilobites.—A study of the appendages of Trilo- 
bites leads Dr. Walcott to views confirmatory of those of Bernard in 
regard to the origin of the Trilobites. Dr. Walcott considers the 
modern Crustacea as “ descendants of the Phyllopod branch, and the 
Trilobita form a distinct branch." (Geol. Mag., May, 1894). 
Bernard's lastest communieation on the subject, is to the effect that 
the great variability in the number of segments shown by Trilobites, 
the formation of the head by the gradual incorporation of trunk seg- 
ments, the bending round ventrally of the first segment, the * wander- 
ing " of the eyes, the existence and modification of the * dorsal organ,” 
and especially the character of the limbs, all serve to connect the 
Trilobites with Apus. That Apus lies low in the direct line from the 
original annelidan ancestor towards the modern Crustacea, and the 
Trilobites probably branched off laterally from this line, anterior to 
the primitive Apus, as forms specialized for creeping, with the protect- 
ion of a hard imbricated carapace. This carapace resulted from the 
repetition on trunk segments of the pleurae of the head segments, which 
together form the head shield. (Proceeds. London Geol. Soc., March, 
1894). 
Some New Red Horizons.—A survey of Montgomery and 
‘Bucks Counties in Pennsylvania, has shown that the New Red in the 
former county is 27,000 feet thiek. This unexpected result harmonizes 
with the recorded facts in other States. A study of this region has 
been made by Dr. B. Smith Lyman with the view of a better under- 
standing of the relative geological position of the different horizons 
from which fossils have been reported in the “ so-called American New 
Red” of the eastern part of the United States. Mr. Lyman recog- 
-nizes in the Montgomery series five distinct horizons which he names 
and defines as follows, beginning with the oldest : 
Shales mostly soft and red, but in small part dark gray or green, or 
blackish with. beds of brown sandstone, and of gray sandstone and 
pebble rock, at rita and eastward, about 6,100 feet ; Norristown 
Shales. 
Shales, in great part hard, dark or greenish-gray and blackish, 
partly dark red, at the Gwynedd and Pheenixville tunnels, with traces 
of coal, about 3,500 feet; Gwynedd Shales. 
p 
————Pá 
