NO. I CAMBRIAN FAUNAS OF EASTERN ASIA 59 



dissepiment toward the apex, a feature also shown by both H. ? ? 

 simplex [plate 5, fig. 11] and H. ? clurius [plate 5, fig. 7]. The 

 coiled gastropods are of unusual interest, as three forms, Mathe- 

 rella ? sp. undt. (C55) [plate 5, fig. 6], Pelagiella chronus (C i, 

 C4, C 18) [plate 5, figs. 9, ga-b], and P. zvillisi (C72) [plate 5, 

 figs. 12, 13] are from the Middle Cambrian. 



Pteropoda. — The species of the genera Hyolithes and Orthotheca 

 are of the usual Cambrian type. I have introduced on plate 6, figure 

 8, a reproduction from a photograph of a Hyolithes (H. carinatus 

 Matthew) that shows the operculum in position, also the support of 

 the fin-like arms so characteristic of recent pteropods. 



Cephalopoda. — One genus and one species from a horizon 480 feet 

 (146 m.) below the summit assigned to the Upper Cambrian are all 

 that are known of this class. The species Cyrtoceras camhria (C 56) 

 [plate 6, figs. 4, ^a-cY is a typical example of the family Cyrtoceri- 

 dse and from its presence we are compelled to consider that there 

 was a large and varied cephalopod fauna in the area, from which it 

 migrated into the Sinian sea. It is a reminder of our want of data 

 on the fauna of the Upper Cambrian and of the great harvest to be 

 gathered by the future field- worker and student of the stratigraphic 

 geology of Asia. 



In the Ozark region of Alissouri in North America Ulrich has 

 found both the Cephalopoda and Gastropoda extensively developed 

 at a horizon not much above that of Cyrtoceras camhria, if we base 

 the correlation on the character of the trilobites in the two distant 

 localities. 



Trilobita. — The exceptional genera of the Trilobita found in China 

 and not known to occur elsewhere are Stephanocare [plate 7], Tein- 

 istion [plate 9], Blackzvelderia [plate 9], Damesella [plate 9], and 

 Drepanura [plate 10]. All other genera are represented in western 

 North America and western Europe, and there is a striking resem- 

 blance even to sfSecific characters in many of the forms. The most 

 noticeable oriiissions of American and European genera from the 

 Chinese fauna are Paradoxides of the Atlantic Basin fauna and 

 Olenoides, Dikelocephalus, and Neolemis of the North American 

 fauna. The closely related genus Dorypyge (to Olenoides) is found 

 abundantly in China, western United States, and on the island of 

 Bornholm in northwestern Europe. 



The genera Ptychoparia, Conokephalina, Acrocephalites, Inouyia, 

 Agraidos, Lisania, Solenoplenra, Anomocare, Anomocarella and 



^ The plate numbers refer to plates accompanying the large memoir on 

 " The Cambrian Faunas of China." 



