(i) 86 Palseontologia Sinica Ser B. 



another from Lincheng, Shantung (F. F. Mathieu), and a fairly well-preserved internal 

 septate mold from Wen Nan, Mon-yin-Hsien, Shantung (V. K. Ting). 



The specific name is given in allusion to the Chinese calculating frame or 

 Suanp 'an (H $) , to the elements of which, i. e. the single row of CM (5) the siphuncle 

 of this species shows a marked resemblance. 



Actinoceras submarginale Grabau (sp. nov.) 



Plate VIII, figs. 5a, b; Plate IX, fig. 3. 



Shell of medium size tapering at the rate of about 1 in 4, the siphuncle submar- 

 ginal and occupying about one-half the diameter of the shell or somewhat less, regularly 



* 



swelling between the septa, and constricted at the septal openings to about two-thirds its 

 width. Endosiphuncle large, its diameter about 3 mm. where that of the siphuncle is 15 

 mm. with deverticula extending into the nummuli. Mural pores not observed. The 

 section of the shell is apparently suboval while that of the siphuncle is circular. It is so 

 close to the shell on one side, that it appears almost to touch it, but the septa are 

 continuous around it, showing that the contact is not absolute. In form the siphuncle 

 tapers gently, the rate being approximately 1 in 19 in a characteristic specimen. 



The septa range from 4 to 4. 7 mm. apart and are, as a rule moderately concave, 

 though in one specimen (Plate IX, fig. 3, cat. no. 56.) some of them exhibit rather 

 marked curvature, involving in some cases as much as the depth of two chambers. The 

 space between the septa ranges from 4 to 4.4 mm. in specimens of about thirty mm. 

 diameter. In a specimen sectioned so as to give the siphuncle a subcentran appearance, 

 although it is in reality close to the margin (Plate VIII, fig. 5a, 6) the septa are at first 

 rather flat-lying, and somewhat undulating, after which, near the margin, they bend 

 strongly forward (upward). In this respect the two specimens figured show a marked 

 contrast, but it must be remembered that they show the shell in sections practically at 

 right angles to each other. 



The stereoplasm is variable. In one specimen (fig. 5) it fills the greater part of 

 the cameras leaving only a narrow space beneath the next septum. The filling extends 

 to the siphuncle and makes the entire shell a very solid and compact mass. In another 

 specimen (fig. 3) the filling is comparatively slight, and the septa hence have weathered 

 out in relief from the section and were readily broken away. 



