Newell.] 



468 



[Jan. 18, 



The septa are smooth, having a concavity equal to an arc of 

 about 110°; the distance apart is one-third the diameter of the 

 shell. The sutures are apparently straight ; the outside of the 

 cast, however, is too greatly weathered to show their exact direc- 

 tion. 



The siphon is large and subcentral ; its diameter at the aperture 

 through the septa is 7 mm. or about one-fifth the diameter of the 

 shell at this place. A longitudinal section gives a few markings 

 which indicate a moderate expansion of the tube in the interseptal 

 regions. 



The characteristic feature of this species is the rosettes (the an- 

 neaux obstrncteurs of Barrande) . These rosettes extend 3 to 4 mm. 



Smallest septum. 



Longitudinal section. 



above and below each septum, and are separated from each other 

 by a space of about 7 mm. The small tube through the rosettes, 

 the endosiphon, somewhat irregular in outline, is a trifle over 1 mm. 

 in diameter. The section through the centre of the rosettes in- 

 dicates their laminated or concentric structure. 



The test is unknown and there is no evidence of ornamentation 

 on the cast. The moderate convexity of the filling of each air 

 chamber is probably due to weathering of the exterior. 



The plane of the illustration does not coincide with the axis of 

 the siphon ; but, at the smaller end of the shell, passes somewhat 

 above the endosiphon, as shown on the half septum at the left of 

 the figure. 



Locality. — Wabash City, Indiana. 



