(i) 24 Paliconlologia Sinica 8er. B 



species are not so high laterally as in E. sinensis, and the shoulder angle is somewhat 

 less pronounced. The sides of the Hupeh form too are less convex, becoming almost flat 

 in the last whorl, and the umbilicus is more depressed than in the northern species. In 

 E. sinensis too, the embracing is much more pronounced so that each outer whorl rises, on 

 its inner margin, above the shoulder angle of the preceding whorl, whereas in E. 

 Icushanensis the shoulder of the outer whorl meets the whorl next within, a very short 

 distance below the shoulder angle. This is shown in the sections on plate II. of which 

 fig. 7c represents the whorls of E. Icushanensis and 8d those of E. sinensis. 



HORIZON AND LOCALITY: The only specimen so far known comes from the 

 Machiakou limestone of Ku-Shan, in Huo-Luh-Hsien western Chihli. This region has 

 also furnished Actinoceras richthofeni from apparently the same horizon. 



Genus ECCYLIOMPHALUS Portlock 

 Eccyliomphalus tangshanensis Grabau (sp. nov.) 



Plate II Fig. 9. 



Shell large, laxly coiled, whorls not in contact, coiling essentially in a plane. 

 Whorls rather rapidly enlarging from about 10 mm. at the beginning, to 25 mm. at the 

 end of the final volution in the type specimen, in which only about one and a half 

 volutions are preserved. Earliest whorls unknown. Under side broadly rounded, inner 

 angle sharp and rectangular outer angle rounded. Upper surface unknown. 



The specimen exposes only the lower side of the whorls which is partly worn. 

 Its large size (maximum diameter about 75 mm.) and rapidly enlarging whorls are 

 however very characteristic features. A section of a second specimen shows nearly two 

 complete volutions but the final portion is crushed inward giving the shell a smaller 

 proportional diameter. The diameter of the final volution is only about 18 mm. at the 

 end, and 7 mm. at the beginning, giving about the same rate of enlargement. This 

 specimen is worn down from the upper side. A comparison of the two specimens suggests 

 an ovate-triangular cross-section of the whorls. Only a portion of the shell is preserved on 

 the under side and this shows indistinct regular lines of growth. In general form and 

 character, and in the rate of enlargement this shell suggests Eccyliomphalus undulatus Hall 

 from the Stones River (late Middle Ordovician) of the central United States. It is 

 however a much larger shell than any member of that species with which I am 

 acquainted. 



