Vol. I. C. C. Y'u — Ordovician Cephalopoda of Central China (ii) G5 



Family LITUITIDAE Noetling 

 Genus LiTUITES Brogniart 

 Lituites lii Yfi (sp. nov.) 

 Plate IX., Fig. 7. 



The shell is a gyroceracone in the young and becomes straight in the adult stage. 

 Section subcircular. This form is represented by only one specimen which occurs in a 

 natural longitudinal section and can not be separated from the enclosing rock. There- 

 fore, nothing is known of the surface ornamentation of the shell. Apertural portion 

 not preserved. 



The coiled part of the conch includes about two volutions. The whorls, are 

 separable about i mm. or a Uttle more near the apical part, and 2.5 mm. at the place 

 where the second or last volution ends and the shell begins to straighten. The diameter 

 of the coiled part measures about 35 mm. from the larger end of the last whorl to the 

 opposite side across the volutions. In the central part of the first volution there is an 

 open space with a diameter of about 7 mm. The straight part of the shell is slightly 

 bent inwards and attains about 70 mm. in length, expanding slowly at the rate of i in 

 22. 



Septa simple, thin, moderately concave. They are more curving forward on the 

 internal or the dorsal side. The intervals between the septa gradually increase toward the 

 aperture. They are about 1/2 the diameter of the shell. At the second volution there 

 are eleven septa in the distance of half a whorl or a length of about 44 mm. Near the 

 larger preserved end they are 9 mm. apart, where the shell has a diameter of 15 mm. 



Siphuncle narrow, tubular, lying dorsal of the center. At the upper portion it is 2 

 mm. distant from the internal side and 11 mm. from the external. In the same stage the 

 widths of the siphuncle and the conch are about 2 mm. and 15 mm. respectively. It is 

 apparently empty, and the septa appear thickened on both upper and lower marginal 

 portion with white organic deposit. 



Remarks: Owing to the fact that the specimen is not well preserved, the generic 

 determination of this form is somewhat doubtful. Foerste said.^ 'Tt is well known at 

 present, however, that the chief characteristic of true Lituites consists of the presence 

 of deep ventral and dorsal sinuses, shallow lateral sinuses and intermediate crests." 

 In our shell the apertural end has not been preserved, whether it is provided with such 

 sinuses and crests or not is not known. Furthermore, the coiled part of this form is 

 also different from that of the genotype Lituites lituus Montfort, which has the 

 volutions entirely in contact. Foerste proposed in 1925 the new generic name 



I. Foerste: Notes on Cephalopod Genera; chiefl}- coiled Silurian forms, p. 18. 



