STRATIGRAPHY OF SHAN-TUNG. AI 
Near the top of the limestone there is a well-preserved assemblage of 
trilobites, with a few other forms characterized by an abundance of Dame- 
sella, two species, and Acrotreta pacifica. ‘These occur in several different 
localities which are not, however, widely separated. ‘This fauna has no 
species in common with the last or with the next succeeding fauna. The 
list comprises: 
Acrotreta pacifica Walcott Blackwelderia alastor Walcott 
Agraulos acalle Walcott Teinistion alcon Walcott 
Artonellus ajax Walcott Teinistion typicalis Walcott 
Damesella blackweldert Walcott Ptychoparia (Liostracus) tutia Walcott 
Damesella bellagranulata Walcott Pterocephalia asiatica Walcott 
Fossils from the upper shale.—Although not sorich in fossils as the lower 
shale, the upper shaly member gives us some very interesting and charac- 
teristic species. Most of the specimens are found in.thin platey limestones, 
interbedded with light gray shales not far below the top of the member. 
The fossils occur on the weathered surfaces of these hard ringing slabs. 
The most striking and one of the commonest species here is Drepanura 
premesmili Bergeron. ‘The large dentate pygidia of Blackwelderia cilix 
Walcott and the smaller ones of Blackwelderia sinensis (Bergeron) are also 
characteristic of this horizon. The entire list from the vicinity of Yen- 
chuang is as follows: 
Acrothele minuta Walcott Drepanura premesmli Bergeron 
Dicellomus parvus Walcott Drepanura kettelert Monke 
Obolus (Westonia) blackweldert Walcott  Ptychoparia? bromus Walcott 
Agnostus chinensis Dames Ptychoparia tenes Walcott 
Agnostus kushanensis Walcott Liostracina krauset Ménke 
Stephanocare richthofent Monke Redlichia finalis Walcott 
Stephanocare sinensis (Bergeron) Redlichia sp. undt. Walcott 
Blackwelderia sinensis (Bergeron) Shantungia spimifera Walcott 
Fossils from the upper limestone.—The uppermost member is very 
nearly equivalent in age to the Ch’au-mi-tién formation of previous 
sections, although it is somewhat thinner. Fossils occur in it at several 
horizons. ‘The oldest fauna of this member was found in a blackish gray, 
partly oolitic limestone, immediately overlying the upper green shale. 
Although not more than 1o feet, 3 meters, vertically, from the last, this 
horizon yielded no species common to the two strata. Here we find: 
Billingsella pumpelly: Walcott Ptychoparia batia Walcott 
Pterocephalia busiris Walcott. Ptychoparia (Proampyx) burea Walcott 
Dikelocephalus? baubo Walcott 
Sixty feet, 18 meters, above the base of the uppermost limestone 
member a gray crystalline layer yields: 
Chuangia nitida Walcott Anomocare bergiont Walcott 
Ptychoparia batia Walcott 
