FORMATIONS AND FOSSILS OF SOUTH MANCHURIA 109 



necks are rather conspicuous, 1 mm or less in length. The interiors 

 of the camerae are almost filled with calcareous matrix, leaving but 

 narrow spaces in its middle parts. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 In the lower fossil horizon of the black banded limestone, near Pen- 

 hsi-hu, Liao-tung, Manchuria. 



Genus GONIOCERAS Hall, 1847 



GONIOCERAS species undetermined 



Plate 22, Figure 4 



I have a small fragment of a thin, straight shell (U.S.N.M. No. 

 83760), which is flat on one face and slightly convex on the other. 

 Though my specimen does not show any part of a thin lateral edge, 

 the outline of the shell suggests that it belongs to Gonioceras. 



Description. — The fragment is 25 mm long, consisting of nine cam- 

 erae in this length. Septal concavity is moderate and its distance 

 averages 2.6 mm. In the vicinity of the siphuncle the septa curve 

 moderately downward, and septal necks are absent. The segments 

 of the siphuncle are strongly depressed vertically from both above 

 and below. Interior of the siphuncle is filled with calcareous matrix, 

 leaving a rather large endosiphuncular passage. Septa are some- 

 what thickened by the deposition of the calcareous matrix on its 

 anterior surfaces. The surface of the shell is smooth. 



Formation and locality. — Middle Ordovician, Ssuyen formation: 

 Lower fossil horizon of the dark gray limestone, just north of the 

 Pen-hsi-hu colliery, Liao-tung, Manchuria. 



TRILOBITA 

 Genus ROBERGIA Wiman, 1902 



ROBERGIA STRIATA, new species 



Plate 38, Figure 8 



A cephalon, lacking the free cheeks, is present in Louderback's 

 collection. It is somewhat rounded triangular in outline and rather 

 strongly convex. The glabella is subtri angular, convex, the width 

 somewhat greater than the length; dorsal and occipital furrows 

 slightly impressed, three pairs of very shallow, narrow, fairly long 

 glabellar furrows are traceable on the posterior half of the glabella ; 

 palpebral lobes small ; frontal rim rather flat and narrow. Surface 

 beautifully striated transversely. 



This species is characterized by its rounded, triangular, convex 

 cephalon and beautiful striations on the surface. 

 101621—32 8 



