lines of the septa, but in reality coincide with them unly partially. On ex- 

 amining the surface of the stone nucleus with magnifier in detail, we see that 

 the suture lines deviate downwards considerably (that is apically) from the lines 

 in question on the two sides normal to the shorter axis of the shell. The shell in 

 longitudinal section shows there are only two moderately concave septa at the 

 base, the remaining upper portion representing the body chamber. The septa 

 are traversed at the center by a broad (12 mm. in diameter) empty tubular space, 

 which is completely shut off from the interior of the camerae by means of the 

 septal necks, these being very long and extending beyond the preceding 

 septum. There is absolutely no organic deposit in the interior of the shell. 



At present the real nature of the impressed lines on the surface is quite 

 obscure to me ; there are two possible explanations : — 



1. If the specimen represents an internal cast of an Ori/ioccras-likc shell 

 the interior of the test must have been provided with sharp annular thicken- 

 ings, and therefore the broad tube is the siphuncle. So far, I am aware of no 

 instance of such annular thickning of the test, on its internal surface, in any 

 known species of orthoceracone Nautilids. 



2. It is also conceivable that the present specimen may represent the 

 siphuncular infilling only of an Ori/iotrrns-Yike shell, and not the stone nucleus 

 of the shell as a whole ; then the impressed lines on the surface of the specimen 

 would be the suture lines of the septa marked on the siphuncle and not on the 

 inside of the shell, and the siphuncle would be divided by septa, as in 

 DifiJiras^moccrns Hyatt, which, however are not complete like those of the 

 genus named, but traversed by a broad central endosiphonal tube. 



The future discovery of test-bearing specimens may reveal the real nature 

 of this striking form. 



Locahty : — No-lu-ping, Tung-hu-hsien, prov. Hu-pei (Usui Coll.) 



Qrthoceras sp. indet. 



PI. XXVIL, Fig. 5. 

 Shell straight, very elongate conical, with an apical angle of about 8° ; ob- 

 long ? in cross section ; surface smooth. Septa moderately concave, about 



