142 How is the Cambrian divided f — Matthew. 
Conocoryphe. Corynexochus. 
Elyx{=Ctenocephalus.) Microdiscus. 
Solenopleura *Agnostus. 
Arionellus, (=Agraulos.) 
Here are fourteen genera of which three are found at high- 
er horizons in the Cambrian system. Under Liostracus the 
Swedish palaeontologists \\\Q\vL(ie Ptychojmria which with Ag- 
nostus has a wide range in the Cambrian system, so that Avith 
the exception of these genera the break is almost complete, be- 
tween this fauna and that which follows. Conocoryphe as un- 
derstood in Sweden does not extend beyond this fauna. 
The third fauna contains the following genera : 
Liostracus? Lep>toplastus. 
OLaNUS.f Eurycare (s.gen. oi Leptoplastus\) 
Faraholina{s,.gen.oi Olenus\). * Agnostus. 
Here all the genera and subgenera are peculiar to this fauna 
except the ubiquitous Agnostus, and Liostracus? 
But the connection with the next fauna is closer than appears 
from the names, as some of the genera are closely related to 
those of the succeeding fauna. Eurycare especially is interme- 
diate between Leptoplastus and Ctenopyge.. 
The fourth fauna has the following genera : 
* Cyclognathus (subgen. oi FeUura\) 
Ctenopyge (s. gen. oi Leptoplastus.\) 
Peltura. SphcBrophthahnus^ (s. gen of Leptoplastus. f) 
Protopeltura, (sub. gen. of Peltura.f ) 
Boeckia (sub gen. oi Leptoplastus.) 
Acerocare (sub gen. of Peltura.f) 
* Agnostus. 
Cyclognathus is found in a fauna above, but Peltura and 
Ctenopyge, with its related forms, especially mark this hori- 
zon. 
The fifth fauna, which has a strong Ordovician facies, exhib- 
its the following genera : 
Cheirurus. Nileus. 
Plioinera. Symphysui'us (s. gen. of Nileus. f ) 
°Harpides. Niohe. 
Remopleurides. ° Iloloynetopus. 
° Triarthrus. Conop)hrys. 
t See Brogger's Etagen 2 und 3. 
