Vol I. Grabau Ordovician Fossils from North China (i) 29 



shoulder. The shoulder itself at the same time becomes more pronouncedly concave, 

 and the peripheral carina becomes more prominent. \ The trispiralled character of the 

 peripheral carina is still maintained, with the median spiral thickest, but the lower spiral 

 becomes more distant, so that the space between it and the median one is slightly wider 

 than that between the median and upper spirals. The space between the peripheral and 

 lower carime has also become more pronouncedly concave. Umbilicus not observed. 



HORIZON AND LOCALITY: Occurs with the preceding. 



Lophospira terrassa Grabau (sp. nov.) 

 Plate II I, Fig. 9. 



Shell of medium size, and somewhat robust aspect; apical angle about G2 degrees. 

 Earliest whorls not preserved. Neanic whorls with a shoulder angle of about 95 which 

 in the adult becomes between 100 and 110. Whorls moderately embracing, leaving the 

 body exposed to a height equalling about half the shoulder width, or somewhat less. 

 Shoulder moderately convave, with a broad and rather ill-defined upper (subsutural) 

 carina and a well-defined sutural shelf or terrace, which -is flat or may slope slightly 

 inwards. Shoulder angle marked by a rounded carina bounded by impressed lines. Body 

 of whorl, below shoulder-angle, gently convex, without lower carina. Lines of growth 

 sharp and crowded, bending at first gently backwards on the shoulder, and then crossing 

 the periphery with a pronounced backward curve. After crossing the periphery, they 

 bend forward, and then more abruptly downwards. They thus indicate a pronounced 

 peripheral notch. Axis with a minute median hollow, as seen in the broken apex. 

 Diameter of final whorl 15 mm. 



This species differs from L. gerardi in the absence of the lower carina, and in the 

 terrassiform sutural shelf. From L. morrisi it differs in the presence of this shelf, and the 

 lesser amount of embracing. It is closely related to Lophospira ampla Ulrich of the 

 Lorraine and Richmond (Upper Ordovician) of the central United States, but that species 

 has a less developed subsutural shelf, and the whorls embrace somewhat more, giving the 

 shell a slightly greater apical angle. The two species are however very similar. 



HORIZON AND LOCALITY: In the Machiakou limestone of Tangshan, Chihli. 

 Survey collection. 



