Vnl I. Grabau OrdoiHcian Fossils from North China (i) 39 



Genus CAMEROCERAS Conrad (emend. Hyatt) 

 Cameroceras styliforme Grabau (sp. nov.) 



Plate IV Figs. 46 



A small slender siphuncle of Cameroceras occurs in the upper or Liangchiashan 

 beds but no portion of the shell remains in the specimens so far obtained. 



A specimen (Plate IV fig. 4) measuring 30 mm. in length, and of suboval 

 tion, measures 3.5 mm. in transverse, and 2.5 mm. in dorso-vental diameter at the 

 lower end. The corresponding measurements at the upper end are 6.6 mm. and 4.8 mm. 

 respectively. The vental side is distinctly flattened. The siphuncle was evidently 

 enclosed by camera.*. Their distance apart near the upper end, as shown by tho 

 annulations, was 2.2 mm. and the angle which these annulations form with the ventral 

 lino of the siphuncle is about 68 degrees. Wall of siphuncle of moderate thickness; 

 interior filled with crystalline calcite, but showing in the center, at the smaller end of the 

 siphuncle, an empty endosiphocoleon of semi-lunar section, its flat base corresponding to 

 the fiat side of the siphuncle. The width of this side is 1.3 mm. while its dorso-ventral 

 diameter is 0.5 mm. (Plate IV fig. 4b). There are three other lumens irregularly placed 

 around the periphery, but equi-distant from the outer wall, indicating that they represent 

 part of an endosiphosheath. * 



Another fragment (Plate IV, figs. 5a-c) representing a larger portion of the 

 iplmncle, measures 7.3 and 5.9 mm. respectively in lateral and dorso-ventral diameters, 

 rhe ventral side is not so much flattened, but is more broadly rounded than the dorsal, 

 he siphuncle at this point was not absolutely in contact with the shell, for the septal 

 e Iges form a distinct, broad, rounded saddle upon the ventral side. Septa 2.2 mm. apart. 

 Siphuncular wall (silicified) rather thick, the interior filled with crystalline calcite, except 

 for a central sheath of similar section as that of the wall of the siphuncle, and like that, 

 silicified. Its diameters, at the upper end are: lateral, 5 mm., dorso-ventral, 3 mm., the 

 limensions of the siphuncle at this end being 7.3 and 5.9 mm. respectively. At the other 

 ml, 8 mm. distant, where the dimensions of the siphuncle are 6 and 5 mm. tho inner 

 tube measures 3 and 1.8 mm. respectively. Thus, while the lateral tapering of the 

 piphuncle is 1.64 mm. in 1 mm. and the dorso-ventral tapering 1.12 mm. in 1 mm., that 

 of the inner tube is 2.5 and 1.5 in 1, respectively. 



A third specimen (Plate IV figs. 6a-c) represents a still larger portion of the 

 siphuncle of apparently the same species. Its length is 13 mm., while the diameters at 







* Sec the foot-note on p. 35 



