488 
ELEMENTS OF GEOLOGY. 
Fossils of the lowest Fossiliferous Beds in Bohemia^ or ‘ ‘ Primordial Zone ” 
of Barrande. 
Fig. 576. 
Fig. 577. 
Paradoxides Bohemicus, Barr. 
About one-half nat. size. 
Conocoryphe striata. Syii. Conocephalus 
striatus, Emmrich. One-half natural 
size. Ginetz and Skrey. 
Fig. 578. 
Agnostus integer^ Beyrich. 
Nat. size and magnitied. 
Fig. 579. 
Agnostus Rex, Barr. 
Nat. size, Skrey. 
Fig. 580. 
Sao Mrsuta, Barrande, in its various 
stages of growth. 
The small lines beneath indicate the true 
size. In the youngest state, a, no 
segments are visible ; as the metamor¬ 
phosis progresses, h, c, the body seg¬ 
ments begin to be developed: in the 
stage d the eyes are introduced, but 
the facial sutures are not completed; 
at e the full-grown animal, half its true 
size, is shown. 
their own dependent on the mnltiplication of their thoracic 
segments and the diminution of their caudal shield or py- 
gidium. 
One of the “ primordial” or Upper Cambrian Trilobites of 
the genus Sao.^ a form not found as yet elsewhere in the 
world, afforded M. Barrande a fine illustration of the meta¬ 
morphosis of these creatures, for he traced them through no 
less than twenty stages of their development. A few of 
these changes have been selected for representation in the 
accompanying figures, that the reader may learn the gradual 
manner in which different segments of the body and the eyes 
make their appearance. 
In Bohemia the primordial fauna of Barrande derived its 
importance exclusively from-its numerous and peculiar trilo¬ 
bites. Besides these, however, the same ancient schists have 
yielded two genera of brachiopods, Orthis and Orbicula^ a 
pteropod of the genus Theca., and four echinoderms of the 
Cystidean family. 
