48 



ART. 2. IT. YAEE : CRETACEOUS 



scribes T. crassus as " Windung seitlich niclit abgeplattet " and 

 7\ sphaeronofns as having " Seitenflächen etwas abgeplattet."'^ 



The jii-esent species being based on a single young specimen 

 represented by an internal cast, the writer is not in a position 

 to draw a distinct line of demarcation between it and T. spliaeronotus 

 or T. (jlabrw^. However a slight difterence in the form of the 

 whorls and the somewhat wider umbilicus of the present species, 

 as compared with the above two, seem to indicate that it belongs 

 to a distinct species. 



Locality: — In a pebble from the Pombets, Prov. Ishikari. 



Horizon : — Unknown. 



TETRAGONITES POPETENSIS m. 



PI. VTI., iigs. 4. a,b, and (1. 



Dimensions :■ 



Diameter. 



ITeiglit (ii" till' last whorl. 

 Breadth of tlie la^t wlmrl. 

 Wndtli of niubilion.s. 



(J) ,:.,i,J 



(2) 



0.4 em. 

 1.4.') „ 

 1.50 „ 

 1.0, „ 



100. 2.0')em. 

 42. 0.1)1» „ 



44. 



no. 



0.90 „ 

 0.55 „ 



100. 

 4.1. 



2fi. 



1) A specimen from the Shi-sanushil)e. (PI. VII. figs., 4 a, b). 



2) A specimen from the Penke-opushikep, a tributary of the 

 Teshiogawa. (PI. VII., fig. C>.) 



Shell discoidal, compi'essed, the smaller specimens measured 

 above, l)eing composed of five volutions. Umln'licns moderate in 

 size; involution about n. Whorls sulxpiadralc in section, inflated 

 ventrally, and the umbilical wall perpendicular. Surface smooth, 

 with exceedingly fine lines of growth. Periodic arrest of growth 



1] .Jnrnri: 1. e. 



