DESCRIPTION OF SPECIES 



Class CEPHALOPODA 



Order NAUTILOIDEA Zittel 

 Suborder Holochoanites H37att 



Family ENDOCERATIDAE Hyatt 

 Genus CAMEROCERAS Conrad (emend. Hyatt) 

 Cameroceras cf. styliforme Grabau 

 Plate I., Figs. 1-3 



1922. Cameroceras styliforme Grabau: Ordovician Fossils from North China, p. 39, pi. IV, figs. 4-6. 



There are a number of black, slender and cylindrical structures adhering to the 

 weathered surfaces of dark gray limestone fragments, collected from western Hupeh by 

 Mr. Hsieh. The exterior of the material has been so deeply eroded that one cannot 

 distinguish in the field what types are represented. After separating it from the rock 

 and slicing it into sections it becomes apparent that we are dealing with the endoconch of 

 Cameroceras, or of Proterocameroceras. These structures are represented only by frag- 

 ments. One of them (Plate I., Fig. 2) measures about 40 mm. in length. Its cross section 

 is slightly oval, being 11. 5 mm. in transverse, and 10 mm. in dorso-ventral diameter at the 

 upper end. The ventral side is slightly flattened. The endoconch is provided with an 

 endotheca, which has been partly preserved through protection from weathering by the 

 country rock. The endotheca is rather thin, and its surface is clearly marked by the 

 ectoseptal edges, which are oblique to the ventral side forming with it an angle of about 

 60". Owing to the fact that the specimen is much eroded, the character of the ectosep- 

 tal annulations on the ventral side is entirely unl^nown, therefore the position of the 

 endoconch is rather uncertain. The ectoseptal distances, as shown by these edges on 

 the lateral side, are very uniform, reaching 2 mm. more or less. In the interior of the 

 endoconch there are some endosepta. The spaces between them are wholly filled with 

 the white crystalline deposit, but the endocone is empty, and assumes a semi-lunar 

 section with a flat base, corresponding to the ventral side of the endoconch. In another 



(II) 23 



