(i) 80 Palseontologia Sinica Ser. B 



expansion, which is more or less continuous across the siphuncle, and into which the 

 several pores of the siphonal wall open. This is well shown in the specimen illustrated 

 in fig. 4 Plate IX, where the end of the siphuncle has been severed off along one of 

 these planes of weakness. 



Aperturally the endosiphuncle terminates in a conical expansion, as described on 

 page 73. It may continue beyond this in a series of hollow nummuli. 



The mural pores of the siphuncle, if they are present in this species, are not well 

 preserved. In a specimen in which they might be expected to appear prominently 

 there appears to be no positive indication of them. This may be merely due to the 

 manner of preservation, or the pores may in reality be absent, or may have been com- 

 pletely filled during the progress of shell growth. 



So far as can be determined from the fragmentary material, the exterior of the 

 shell is without ornamentation except fine flexuous longitudinal lines. 



Comparisons. Freeh compares this species with a fragment figured by Barrande * 

 under the name Orlhoceras (Actinoceras) richardsoni from Little Manitoulin or Cockburn 

 Island Lake Huron, Canada, and calls attention to the fact, that Barrande 's specimen 

 can not be regarded as belonging to A. richardsoni Stokes. This would suggest that the 

 Chinese species, or a closely allied but unnamed species, also occurs in the early Upper 

 Ordovician (Trenton) of North America. I know of no other described species with 

 which our Chinese form can be compared. 



HORIZON AND LOCALITIES : In the Machiakou (Upper Tsinan) or Adinoceras 

 limestone, widely distributed in north China. The type comes from Hsiau-sorr, Feng- 

 tien, (Manchuria), and was collected by von Richthofen in 1869. Yabe cites the species 

 as common at Kwa-sen-do, Ko-to-gun, Hei-an-nan-do, in Korea.** In Chihli province 

 it has been obtained from Tangshan, Machiakou, and Chaokouchuang, all in the Kaiping 

 basin, and from Huo-Luh Hsien in the southwestern part of the province (by Miss Clarke). 

 In Shantung province it has been found near Lin-cheng by .Dr. F. F. Mathieu and at 

 Seng Chuang, Ningyang district and Wen Nan, Monyin-Hsien, by Dr. Ting. 



Actinoceras tani Grabau (sp. nov.) 



Plate VII, figs. 4 - 7. 



Shell slender, tapering at a rate varying from 1 in 5 to 1 in 7 according to the 

 direction of the section measured. Cross-section faintly oval. Siphuncle excentric, on 



* Syat. Sil. de la Bohfime, Vol. II Text III. 187-1, p. 737, pi. 234, figa. 2, 3. 

 ** Pal. Southern China 1920, p. 54, footnote. 



