Vol I. Grabau — Ordovician FoksHs from North China (i) 85 



endosiphuncle seems to be obliterated by filling. Camerse fairly uniform, their length 

 averaging perhaps 3.5 mm. where the shell has a diameter of 15 mm.; nor do they 

 materially increase with the increase in the shell diameter to 20 mm. Their concavity is 

 nearly equal to the depth of two chambers. Stereoplasmic filling of the cameras is 

 pronounced in the earlier part of the shell, but becomes less so in the later camerte. For 

 the most part it is added to the anterior portions of the septa, but in some cases it 

 appears also to be added to their posterior surfaces, but this is very irregular and may be 

 a secondary deposit. The septa are sometimes undulating, in some cases bending back 

 nearly to the center of the nummulus of the preceeding camera. In some cases the 

 stereoplasm ends near the siphuncle in a saucer-like surface as in A. tani, while in other 

 cases it extends nearly or quite to the nummulus. In still other cases it is more weakly 

 developed in one part than in another of the same camera (see the section Plate 

 VIII, fig. 3). 



Outer surface of shell unknown. 



This species has the general form and character of A. tani, but the cameraj are 

 about half again as long as in specimens of that species of the same diameter, and the 

 concavity of the septa is much greater. The stereoplasmic filling is also more irregular in 

 the present species than in A. tani. 



A fragment of a shell 8 cm. in length, and apparently of this species was obtained 

 from Wen-Nan, Mon-Yin-Hsien, Shantung. This is figured on Plate IX (figs. 1 a-b). 

 The rate of tapering is not ascertainable with accuracy because the shell is slightly 

 crushed on one side, but appears to have been about 1 in 7. At the lower end of the 

 fragment, where the diameter is about 19 mm, the siphuncle has a diameter of about 8.5 

 mm. whereas that of the sections figured is about 7 mm. 



The distance from the ventral margin is 3.5 mm. that from the dorsal 7 mm. 

 Where the diameter of the shell is 24 mm., the distance of the siphuncle from tlie ventral 

 margin is still 3.5 mm. The average distance between the septa is 3.5 mm. The sutures 

 visible on the exterior of the inner mold, are somewhat undulating, extending forward 

 on the ventral side (the side to which the siphuncle is closest) in a gentle saddle, to the 

 extend of about 1 camera-length beyond the lateral and dorsal sides. In the earlier 

 portion, this saddle is less pronounced, its increase in length thus corresponding to the 

 proportional approach of the siphuncle to the ventral side. The concavity of the septa in 

 the larger portion of the fragment is equal to about the depth of two c*amer. 



HoEizoN AND Localities: In the Machiakou limestone of Tai-an, Shantung 

 province. Survey collection. A small specimen apparently representing the apical 

 portion of this species was obtained from Sen Chuang, Ning Yang, Shantung, and 



