87 



resemblance to Troclioccras optatum Bark.^^ and the allies in its general outline 

 and surface sculpture. Its ill preservation, however, prevents further detailed 

 comparison for specific identification. 



The shell consists of a few evolutc (depressed trochoid ?), rapidly enlarg- 

 ing whorls, with its last portion free ; the shell surface bears rather distant 

 acute costae curving backwards on the side-; the costae die out gradually to- 

 ward the aperture, being replaced by crowded finer striae on the free portion 

 of the whorls. 

 Dimension : — • 



Diameter of closely coiled portion. 42 mm. 



Diameter of umbilicus, corresponding to the former. 17 mm. 



Height of whorl, corresponding to the former. ' 13 mm. ? 



Diameter of shell, free portion of whorls included. 50 4- mm. 



Length of free portion of whorls. 23 mm. 



Height of aperture. 19 mm. 



Owing to the great deformation the specimen had suffered, the above 

 measurements of course lack sufficient exactness. 



Locality : — Huang kuo-chi, Ta-kuan-ting, prov. Yun-nan (Yamada Coll.) ; 

 in a dark grey shale. 



Geological Age ; — Probably Gotlandian. 



The presence of Trochoceras in Chinese Gotlandian fauna is interesting, 

 for the group is especially well represented in Bohemian rocks, and seems 

 to give some hint as to the faunal affinit}^ between the southern Chinese and 

 the Bohemian Gotlandian. 



Orthoceratidse. 



Orthoceras Breyn. 

 Orthoceras sp. indet. 

 PI. XVIIL, Fig. 8. 

 This is also too ill preserved and does not allow specific identification ; it 

 represents a long conical tube with an apical angle of 13°; the total length 



1) Barrage: Systeme silurien du centre de la Boheme. Vol. II., p. iii, pi. XXIII, figs. 5-10. 



