306 NEW YORK STATE MUSEUM 



which sHghtly disperse in a forward direction. The low ribs are 

 evidently the remains of the ribs of the convex side of the endosi- 

 phocone, noted below. 



Holm describes the middle portion of the endosiphocoleon 

 which proceeds from the apex of the endosiphocone as possess- 

 ing a very distinct and beautiful sculpture, consisting of growth 

 lines. " These growth lines form an arch, which is strongly 

 bent backward. Their form and curvature corresponds exactly 

 with the outline of the apex of the ' Spiess ' and thereby with 

 the outline of the fleshy end of the siphon. On the anterior 

 portion of the blade there also occur longitudinal lines which 

 intersect the growth lines." Our material fails to show these 

 growth lines so distinctly, but from the fracture lines of the 

 oblique lamellae composing the wall of the endosiphocoleon we 

 infer that they may be the intersections of these lamellae with 

 its surface. 



This middle part of the endosiphocoleon is on both narrow 

 edges [see pl.7, fig.i ; pl.9, fig.i ; text fig. 14] flanked by strong deep 

 black conchiolinous semicylindric rods or wings, [w of figures] 

 which, on the upper and lower side of the blade, quite abruptly 

 change into a layer of dark gray limestone, such as composes the 

 endosiphocone or last endocone. They correspond to the winglike 

 lamellae, which according to Holm begin on the endosiphocone and 

 continue along the endosiphocoleon and which we shall discuss later. 



The further development of the endosiphocoleon can be best 

 described by the use of a series of sections which were made 

 apicad of the part of the endosiphocoleon reproduced on plate 7. 

 These sections are figured on the same plate and diagrammatic 

 sketches illustrating the further stages of development are inserted 

 in the text [fig.5-12]. 



