384 > NEW YORK STATE MUSEUM 



PLATE 13 



Piloceras explanator Whitfield 



1 Lateral view of the endosiphocone of the specimens figiired on 



plate 10. Natural size 



2 Section close to the apical end of the latter showing- the last 



endosiphosheath and the internal conchiolinous lining of the 

 same (endosiphocoleon). Natural size 



3 Longitudinal section of a siphuncle, showing the endosiphocone 



filled with dark matrix and bounded by the last endosipho- 

 sheath ; the swelling of the apical part indicative of a nepionic 

 bulb ; the cameras on the right hand side and the endosiphofun- 

 icles as white bands extending from the endosiphosheath to the 

 ectosiphuncle (enlarged in figure 5). The endosiphocoleon is 

 cut (somewhat obliquely) through its minor axis and shows 

 its dark (more or less conchiolinous) wall, extending to the 

 point of its passage into the endosiphocone. 



4 The same. Enlargement (x5) of the section of the endosipho- 



coleon 



5 The same. Enlargement (x5) of an endosiphofunicle, to show 



its connection with the endosiphosheath (on left hand side) 

 and- with the ectosiphuncle (on the right hand side). The figure 

 shows also the extension of the septal neck in the ectosiphuncle 

 beyond the preceding septum. 



