116 PROCEEDINGS OF THE AMERICAN ACADEMY 



Cock's Head, which is well known as a landmark to the navigator of 

 the Yang-tse. There are three subdivisions of this formation : — 



a. The lower limestone. Hard, silicious varieties of light gray and 

 reddish colors, carrying frequently an abundance of chert, prevail. 

 The thickness of the layers varies from that of card-paper to many 

 feet. The chert nodules increase in some places so much in quantity 

 as to form complete layers by themselves, and lenticular masses of 

 chert are frequently embedded in a soft calcareous sandstone inter- 

 stratified in thin beds between the limestone. Traces of fossils may 

 often be found in them. The limestone itself is frequently filled with, 

 and in certain layers nearly made up of, the shells of a Fusulina 

 which is distinguished from Fusulina cylindrica only by its more 

 perfect cylindrical shape. I collected many beautiful specimens of it. 

 This lower limestone is about fourteen hundred feet thick. 



b. A series of black sandy shales, black lydite, and soft sandstones. 

 The lowest strata are highly fossiliferous, chiefly at Tso-dsu-kang 

 near Ching-kiang, which is the before-mentioned distinguished local- 

 ity. Large specimens of Productus semireticidatus, with shell, interior 

 structure, and spines well preserved, would be sufficient for themselves 

 to indicate the age of the mountain-limestone. They are accompanied 

 by numerous other brachiopods, bivalves, corals, and Fenestellas, the 

 latter being quite a> prominent feature. I collected sufficiently to give 

 pleasant occupation to a geologist who would take the trouble to work 

 up the material. The place where they were found is quite a curi- 

 osity. There are a number of abandoned shafts, the waste dumps of 

 which afford an easy opportunity for collecting the fossils ; otherwise 

 they could hardly be discovered, as the ground is covered by vegeta- 

 tion. As no reason for mining is apparent, it would at first seem as 

 if a past generation had opened the shafts for the delight of future 

 stray geologists, until one hears that these were flint-mines ; indeed, 

 lenticular masses of chert are quite frequent in the soft strata. I may 

 mention, besides, that among the fossils here found are none of those 

 brachiopods which have been long since famous as an article of trade 

 in the Chinese drug-stores. I believe, for various reasons, that they 

 are derived from the Si-hio limestone before mentioned. The soft 

 sandstone which follows higher up in this series carries a bed of coal, 

 the lowest in position which I have found. All the mines once 

 opened on this bed are abandoned, evidently at or little below water- 



evel. But the coal appears to be of inferior quality, and not more than 



