(ii) 46 Palppontologia Sinica Ser. B. 



sharp impressed annular lines are clearly shown, each one probably representing 

 an ectoseptum. They are very crowded, and the distances between them vary to 

 an extremely small degree, ranging from 11.5 to 12.5 mm. Generally sixteen camenB 

 are present in a length of 200 mm, while the ectoconch has a diameter of 66.5 mm. 

 The ectoconch gradually diminishes its diameter toward the apical extremity at the rate 

 of I in II. 5. On examining its sections no other features may be recognized except 

 the scar of the endoconch, which is more or less elliptical in shape and situated close 

 to the outer shell. Test not preserved at all. 



Since we know nothing about the tubi, the actual size of the endoconch and other 

 features, specific and generic determination is impossible. On account of the large, 

 marginal endoconch and the uniformly separated ectosepta, which are somewhat related 

 to Vaginoceras unijorme, it is provisionally put in the genus Vagni ceras. 



Horizon and Locality : From the red bed north-east of Pei-hu-fu, Pu-chi-hsien. 



Suborder Orthochoanites Hyatt 



Family ORTHOCERATIDAE M'Cov 



Genus ORTHOCERAS Breyn 



Orthoceras chinense Foord 



Plate III., Figs. 5a-b; Plate IV., Figs. 4a-b; 



Plate v., Figs, ja-c; Plate VI., Figs, la-b, 2a-c. 



1856. Orthoceras sp., S. P. Woodward: Quart. Journ. Geol. Soc. Vol. XII, p. 37S, pi. VI, fig. i. 

 1888. Orthoceras chinense, Foord: Catalogue of Fossil Cephalopoda. British Museum. I. p. 100. 

 igri. Orthoceras chinense, Freeh: Richthofen's China, Vol. V, p. 8, pi. It, figs. 2 a-c. 

 1920. Orthoceras chinense, Yabe et Hayasaka: Palseontology of Southern China, p. 48, pi. XXVII, 

 figs. 3 a-b. 



Shell (PI IV., Fig. 4) straight, subcylindrical. Section circular. The preserved 

 fragment tapers at the rate of 1:9. Both the initial portion and the larger end are 

 wanting. 



The septal interval gradually increases orad from the smaller extremity. After a 

 certain distance it slightly reduces and immediately increases again. On the whole the 

 camerpe become deeper as the shell expands in diameter, being approximately equal to 

 one half the maximum width of the shell or even a little less. At a point not far from 

 the living chamber the septa become more crowded toward the aperture. The septal 

 necks are very long, extending apically for a distance equal to about one half the inter- 

 space between the septa. Septa thin, direct, having a concavity of 1/2 the depth of a 

 camera or more. 



