32 RESEARCH IN CHINA. 
that deposits of finely divided calcium-carbonate are slowly changed by 
the processes of metamorphism into crystalline limestone and marble.* 
Fossils from Ch’ang-hia limestone.—The Ch’ang-hia limestone yields 
fossils at several horizons. Much of the series is barren, but fossils may be 
expected in greater or less abundance, in almost any of the strata from 
bottom to top. As a rule the more oolitic layers do not furnish many 
fossils, while, on the other hand, some of the non-oolitic strata contain an 
abundance of them. The fossils are always fragmentary; not once, in all 
our collecting in this district, were we so fortunate as to find a single com- 
plete trilobite. Since the fossils are dark bodies in a gray matrix, they 
are easily seen on freshly broken surfaces. 
In the vicinity of the village of Ch’ang-hia, the massive cliff-making 
limestone, which is the most prominent member of the formation, is 
separated from the underlying Man-t’o shale by 24 to 30 meters of thin- 
bedded gray limestone, which is more or less oolitic in certain layers. 
Fossils are rather common in this limestone at several different horizons. 
We have one lot from the basal layers which includes: 
Orthis (Plectorthis) agreste Walcott Ptychopania titiana Walcott 
Ptychoparia (Liostracus) toxeus Walcott Ptychoparia tenes Walcott 
Another small collection from the middle of this thin-bedded member 
possesses no species in common with the last, although the two horizons 
are only 15 meters apart. The reason for this complete change of 
faunas in so slight a vertical range is not obvious; since the character 
of the rock indicates general uniformity in the conditions of deposition, 
we should expect a gradual change in the fossils contained, rather than 
an abrupt one. The list from this upper bed comprises: 
Acrothele rarus Walcott (?) Anomocare tatian Walcott 
Orthotheca daulis Walcott Anomocare ertopia Walcott 
Agraulos abrota Walcott Ptychoparia theano Walcott 
This thin-bedded gray limestone is followed by a massive, hard, cliff- 
making limestone, 60 meters thick. The rock is dark gray, often pur- 
plish or stained brown with iron oxides. It is the principal horizon 
for the peculiar black oolitic bodies mentioned above. On account of 
the difficulty of working with such massive strata, and also because the 
rocks are relatively barren, we found few fossils in this member. 
Two small lots from the top of the cliffy limestone, as exposed east of 
the village of Ku-shan, have yielded: 
Agraulos dryas Walcott Crepicephalus magnus Walcott 
Dorypyge richthofent Dames 

* For an account of these processes see U. S. G. S. Monograph xtvi1, A Treatise on Metamor- 
phism, Van Hise, pp. 796-797. 
