54^ NEW YORK STATE MUSEUM 



Piloceras explanator Whitfield 



Page 42g 

 See pi. 1 1 



I A large specimen retaining the apical portion, which is brokerr 

 lengthwise and exhibits a section of the siphuncle ; the latter 

 being filled with calcite. Above this the break shows the ex- 

 terior of the siphuncle with the septal ribs. The upper part 

 retains the smooth exterior of the shell on the left side ; and 

 on the right side a marginal section with the septa is shown^ 

 The apparent irregularity of the septa is due to that of the breaks 

 producing the section. A natural section of this specimen \s 

 reproduced on the next plate. 



The original is from the Fort Cassin beds at Valcour N. Y.. and 

 now in the New York State Museum. 



