Pennsylvania Geology Final Report Volume 1 1981

196 GEOLOGICAL SURVEY OF PENNSYLVANIA,
Of Crustaceans five genera (8 species have been found in
the Lower Cambrian zone, viz., Isoxys, Lepei'ditia, Aris-
tozoe, Nothozbe and Protocaris. It is as wonderful as anything
else in geology, finding thus a world of schrimx^s in
the first hour of the long day of the planet's life.^
Trilobltes,
one- third of
of 16 genera (53 species), constitute nearly
the entire Lower Cambrian fauna ; trilobiles
with eyes, and trilobites blind ; trilobites wdth facial sutures,
and trilobites with unjointed faces or head shields : Ag^nostus
(3), Microdisciis (8), Olenellus (7), Olenoides (3),
Zacanthoides (2), Bathynotvs (1), Atalonia (1), Cono-
coryphe (2), Ptychoparia (10), Agraulos (3), Crepicephalus
(2), Oryctoceplialiis (1), Anomocare (1), Protypus (4),
Solenopleura (5 species). +
*0f the true crustaceans Lej)erditia derinatoides has two representatives in
the Middle zone. Isoxys is a new genvis. Aristozoe has not been tound in
the Middle zone, but in Europe it has many Silurian species. Of the Phyllopod
crustaceans P)'o