380 NEW YORK STATE MUSEUM 



PLATE 11 



Piloceras explanator Whitfield 



1-7 Transverse sections through the siphuncle, figured on plate 10. ,^ 

 Natural size ' f| 



I Showing the more distant earlier endosiphosheaths and more 

 closely arranged last endosiphosheaths (of adult individual) 

 and the endosiphofunicles. 



^ 2 The small flat endosiphocoleon in the center and a well developed 



system of endosiphofunicles extending from the first endosi- : 

 phosheath to the outer wall. At the right hand side an | 

 endosiphofunicle, which is branching several times in outward j 

 direction (enlarged on plate 12, figure i). \ 



3 Shows another distinctly branching endosiphofunicle on upper i 



side (enlarged on plate 12, figure 2), which well exhibits the 

 relation of the endosiphosheaths to the endosiphofunicle. 

 4-6 Show the decrease in the number of endosiphosheaths (by 

 resorption or alteration in calcite?) and of the endosipho- 

 funicles in apical direction. 



4 This section shows at the lower right hand side an endosipho- 



funicle which distinctly passes through an endosiphosheath 

 that is bent outward at the point of intersection (enlarged 

 on plate 12, figure 4). 

 5, 6 Endosiphofunicles springing here principally from the cor- 

 ners of the endosiphocoleon. 

 7 The endosiphocoleon is not any longer shown since the center 

 of the siphuncle is here worn away. 

 Originals from the Beekmantown beds at Fort Cassin Vt. 



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