64 BULLETIN 16 4, UNITED STATES NATIONAL MUSEUM 



siphuncle is 11 mm, while that between its dorsal surface and the 

 corresponding surface of the siphuncle is 7 mm. This point is about 

 34 mm above the base of the specimen, and here the situation of en- 

 dosiphuncle is somewhat excentric. Since the interiors of both the 

 endosiphuncle and of the siphuncle are completely filled with cal- 

 careous matrix, the internal structure can not be determined. 



A second specimen 59 mm long has a 32 mm diameter of the 

 siphuncle at the top of the specimen. A lateral view of this second 

 specimen and two transverse sections, one of which is at the top of 

 the specimen and the other 27 mm below, are also figured. The 

 lower transverse section shows two, or possibly more, of the older 

 endosyphosheaths. 



CoTYi'parisons. — This species is closely related to Piloceras platy- 

 ventrum Grabau, which has four transverse annulations in a space 

 of 10 mm, while my species has 2.5 annulations in the same space. 

 Grabau's third specimen (not figured), from which he took the sec- 

 tions printed on page 48 of his paper (Grabau, 1922), probably 

 belongs to this new species. 



Formation and locality. — Upper Canadian, Santao formation: 

 Light gray limestones above the second tunnel, 1 mile north of 

 Pen-hsi-hu ; and in the black banded limestone near Tai-chia-pu-tzu, 

 2 miles west of Chiao-tou station, Liao-tung, Manchuria. 



Eolotype and paratype.—U. S. N. M. Nos. 83678 and 83679. 



Family PILOCERATIDAE 



PENHSIOCERAS, new genus 



Diagnosis. — Breviconic orthoceracones with large, stout, spindle- 

 shaped siphuncle, which is surrounded by a definite wall or siphunc- 

 ular shell ; with conical apical end. Siphuncle filled with endosipho- 

 sheaths and calcareous matrix, so the detailed structure of the 

 interior is not shown. The cross sections of the siphuncle and 

 endosiphocone are apparently circular. The endosiphocone is long, 

 conical, alveolar toward the apex and it rapidly tapers into the 

 endosiphotube at the comparatively younger part. 



In none of the specimens so far obtained is the camerate portion 

 preserved. The surface of the siphuncle is apparently annulated. 



Comparisons. — Comparing the structure of Penhsioceras with that 

 of other cephalopods, I am at once reminded of Chilioceras and 

 Piloceras. But the new genus differs from Chilioceras in having: no 

 trace of a triploia endocone (no traces of lateral and main cavities). 

 Penhsioceras is also readily distinguished from Piloceras in having 

 a narrower endosiphocone and a spindle-shaped siphuncle. 



Genotype. — Penhsioceras fusiforme^ new species. 



