(r) 40 Palssontologia SiniCa Ser. B 



the larger end are 10 and 9 mm., and the corresponding measurements at the smaller end 

 8.2 and 8 mm. respectively. The corresponding measurements of the endosiphuncle are: 

 upper end, 5.7 mm. and 4.7 mm., lower end, 2.5 mm. and 2 mm., respectively. 

 Although somewhat compressed, there is no flattening of the siphuncle and the septal 

 ends, which still adhere to the silicifield siphuncle, form only a very gentle obliquity with 

 its axis. This indicates that the siphuncle at this stage was no longer in contact with the 

 wall of the shell, but had been surrounded by the camera on all sides, including the 

 ventral. This is further shown by the fact that the ends of the septa still remaining, are 

 stronger on the ventral side (side of forward convergence) than elsewhere. The septa 

 average about 2 mm. apart. 



In spite of the variations here shown, I am disposed to think that we are dealing 

 with one species only. This is however quite distinct from the species found in the lower 

 horizon (i. e. Proterocameroceras mathieui). 



HORIZON AND LOCALITY: A number of fragments were obtained by Dr. F. F. 

 Mathieu from the upper or Liangchiashan limestone of Liang-Chia-Shan. near Ching- 

 wangtao, eastern Chihli. The age is late Lower or perhaps early Middle Ordovician. 

 Geol. Survey collection cat. nos. 103 to 107. 



Genus SUECOCERAS Holm 

 Suecoceras yehliense Grabau (sp. nov.) 



Plat IV, Figs. 7a, b. 



Represented only by the apical portion of the endosiphuncle which shows the slight 

 but distinct inflation characteristic of the genus. The most perfectly preserved specimen 

 (Plate IV, fig. 7), has a length of about 40 mm. Its apex is pointed and its diameter 

 increases rapidly at first, then more slowly, until at a point about 20 mm. from the apex, 

 it has a diameter of 13.2 mm. Then it decreases slowly, its diameter at the upper end 

 of the specimen being 12.5 mm. A second specimen shows a maximum diameter of 11.3 

 mm. at a point about 20 mm. above the apex and then decreases to 10.5 mm. at a 

 distances of about 28 mm. from the apex. 



Neither specimen has the surface well preserved, but on the larger one the oblique 

 septal lines are indicated in the apical portion. At first they are 1.5 mm. apart, this 

 distance increasing to nearly 2 mm. shortly after. The obliquity of the septal lines, with 

 reference to the axis of the shell, is 55 degrees. 



