48 RESEARCH IN CHINA. 



tion from a photograph of a Hyolithes (H. carinatiis Matthew) that shows 

 the operculum in position, also the support of the fin-like arms so character- 

 istic of recent pteropods. 



Cephalopoda. One genus and one species from a horizon 480 feet ( 1 46 m . ) 

 below the summit assigned to the Upper Cambrian are all that are known of 

 this class. The species Cyrtoceras cambria (C56) [plate 6, figs. 4, $a-c\ is a 

 typical example of the family Cyrtoceridae and from its presence we are com- 

 pelled 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 Missouri in North America Ulrich has found both 

 the Cephalopoda and Gastropoda extensively developed at a horizon not 

 much above that of Cyrtoceras cambria, if we base the correlation on the char- 

 acter 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], Teinistion [plate 9], 

 Blackwelderia [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 resemblance even to specific characters in many of the 

 forms. The most noticeable omissions of American and European genera 

 from the Chinese fauna are Paradoxides of the Atlantic Basin fauna and 

 Olenoides, Dikelocephalus, and Neolenus 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, A croce.phalites, Inouyia , A granlos, 

 Lisania, Solenopleura, Anomocarc, Anomocarella, and Coosia are well repre- 

 sented in China, western North America, southwestern United States, and 

 northwestern Europe. Bathyuriscus and Asaphiscus are essentially Pacific 

 Basin types. They represent the most advanced forms of the Trilobita of 

 Middle Cambrian time and may be compared with Asaphns and Bathyurus 

 of the Ordovician fauna. 



Redlichia is an intermediate form that serves in a limited degree to con- 

 nect the Mesonacidae [Walcott, 19100] and the Paradoxidae. Its tapering gla- 

 bella and elongate eye-lobes recall those of Ncvadia, and its small pygidium 

 that of Holmia and Cattavia [see Walcott, 19100, plate 44]. 



Many species of trilobites are represented only by fragments of the 

 cephalon, scattered segments of the thorax, and pygidia that can only be 

 tentatively designated as probably belonging to the same species as an 

 associated cephalon. In some instances the cephala of otherwise distinct 

 genera are so nearly similar that in the absence of the thorax and pygidium 

 they would be referred to one genus. This is particularly the case among 

 the genera of the Ptychoparidse. 



