404 Tiie Aiiievicdn Geologist. June, 1897 
or may bf represented in depauperated or greatly modified 
forms. Both of the Scotch species of Olenellus are small, and 
they are associated with a minute trilobite [Olenelloides) al- 
lied to the olenellids, but showing some remarkable larval char- 
acters in the adult, as cylindrical glabella, lateral cephalic 
spines, short pleurae. But with these are others of advanced 
type, as long posterior lobes to the cephalic raehis and short- 
ened eyelobes. 
With this single genus of trilobites there are a Hyolithes 
and a Salterella. the whole forming, with Olenellus, a very 
meagre fauna. But on the western side of the Atlantic this 
fauna was reinforced by numerous forms from various classes 
of the animal kingdom; among the trilobites are Solenopleu- 
ra, Ptychoparia, Agraulos,* genera which range from the 
horizon of 0. bi'oggeri in Newfoundland (also from just beneath 
Paradoxides in Bohemia) upv/ard through the Paradoxides 
beds. 
This enriched fauna is replete with genera which find their 
home in the Paradoxides beds both in the lower and upper 
part. 
Following this fauna further west, the associated trilobites 
in Nevada have a still more modern aspect ;f we are therefore 
tempted to think that Peach is right in his foreshadowings of 
the migration of this stock. 
But at the same time is there not some meaning in the as- 
sociation of so many paradoxidean genera with the Olenellus 
fauna, genera which it appears to have picked up in its jour- 
ney from the east J (supposing it to have come from that direc- 
tion). 
On the same ground one might conjecture that there had 
been a migration of the O. michwltzi branch ; for that species 
is small compared with O. calUivii. and O. broggeri, and it 
*The early species referred to the genus ( chiefly sub. gen. Strenuella) 
are not very closely related to the typical faunas in the Paradoxides. 
beds; Pi-otagraulos of the Protolenus fauna is nearer the line of devel- 
opment of the typical species. 
'\Olenoides quadriceps, Zacanthoides Icevis. Piychoparia subcoro- 
Hata (like a Euloma or Anomocare), Crepiceplialiis augusta, C. lilimia 
with pygidium spined like those of the Upper Cambrian, Oryctocepha- 
lus primus, with olenoid glabella and complicated pygidial structure. 
JThe writer's views relative to the possible cotemporaneity of the 
Olenellus and Paradoxides faunas, are outlined in Trans. Roy. Soc. 
Can., vol. X, sec. iv, p. 10. 
