50 ART. 2. IT. YAP.E : tRRTACEOUR 



Geueral shape as in T. spliaeronotus. Umbilicus moderate in 

 size, surrounded by a perpendicular wall. Involution about i. 

 Whorls rather slowly growing, subquadrate in cross-section, some- 

 what broader than high and broadest near the umbilical margin. 

 Surface smooth, but with periodic arrest of growth, indicated by 

 inconspicuous round ribs of which four have lieen counted on the 

 last half of the outer volution. The character of the ribs is the 

 same as in T. glahrus and T. sphaeronotus being distinguished only 

 by a somewhat more oblique course. 



Suture as in the preceding s])ecies. 



The Japanese specimens agree quite well with those described 

 by KossMAT under the name of T. epigonus from the upper 

 Trichinopoly group of Andur and Varagur, S. India. The l)ody 

 Avhorl of the larger Indian specimen figured by Kossmat measures 

 2.6 cm. high and 2.7 cm. broad, and its umbilicus 1.5 cm. in 

 width, the diameter of the shell itself being 5.9 cm. Among the 

 Japanese specimens there is none which attains such a large size. 

 But they are comparable to, and agree in every particular, with 

 the smaller ones of T. epigonus also figured by Koss:\rAT. The 

 periodic arrest of growth is sometimes entirely absent and 

 sometines present on the young shells of T. epigonus, so that 

 this seems to be of no. special importance in the distinction of the 

 species. In the specimens in the writer's collection, the periodic 

 i'il)S are shown with moderate distinctness and their number 

 agrees with those of the larger specimen figured by Kossmat. 



