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Geology of the Bosphorus. 187 
fossils have been found which are rather characteristic of the 
per Silurian period, and the rich deposits which have been 
discovered by Mr. Forbes and myself at Hissar and Baltali- 
man appear to belong chiefly to this earlier formation, although 
they contain fossils usually considered as Devonian. 
t seems probable, upon the whole, that in this vicinity there 
was no clearly marked separation between the Upper Silurian 
“The fossils and rocks of the Bosphorus have a remarkable 
resemblance to the Silurian deposits of Bohemia.” Tchihatcheff 
notices that he has a specimen from Caudlijah upon whic 
are found a Devonian brachiopod (Chonetes sarcinulata) and 
a Silurian trilobite (Phacops longicaudatus). We have ourselves 
a single specimen three inches square found at Baltaliman, 
which exhibits a perfect pygidium of Phacops longicaudatus, a 
Pi lewrodyctium problematicum and a Spirifer subspecrosus. These 
admissions of Abdullah Bey, de Verneuil and T’chihatcheff, and 
these facts, certainly confirm the views exp above as to 
the age of the rocks of the Bosphorus. Another fact of at least 
negative value is that no trace of fish and no sufficient evidence 
of the existence of plants has ever been found in these rocks, 
h of which might be expected in the Devonian perio’. 
he principal rocks found in this formation are sandstones, 
shales, and limestones, with more or less quartz either in veins 
