1916.] J. HORNELL: Indian Varieties and Races of Turbinella. 117 
shell substance of the Rameswaram material is harder and takes a better polish than 
even the regularly grown handsome Tuticorin shells. This is due to the slow rate of 
growth characterizing these shells; the depth at which they live, 44 to 54 fathoms, 
and the large amount of mud in suspension in the water around them, renders their 
habitat less favourable for growth than the deeper water and clean sands, densely 
stocked with polychaets, found in the Tuticorin area (Pl. X, fig. 3). 
The mean apical angle is 83 3°, as against an average of 77°8° for Tuticorin and 
779° for Kilakarai. The shells are decidedly shorter in the spire than either of the 
other two races and as already stated they scarcely ever attain a large size; 54 x 3 
inches diameter is nearly a maximum for those fished in the offshore beds lying in 44 
to 54 fathoms. It is notable that shells from inshore beds, 2 to 3 fathoms, grow to 
a larger size than those from the deeper beds. Except in the case of shells found in 
the inshore beds on rocky ground, the columellar plicae are not usually strongly de- 
veloped, in this agreeing with the Tuticorin shells. Towards the west these shells 
spread along the shore of the mainland as far as Pillaimadam, a place eight 
miles west of Pamban Pass, where they begin to mingle with the Tirupalagudi race 
A. By 
Fic. 3.—Spire of var. comorinensis (A) seen in profile for comparison with (B) profile of var. acuta, 
Tuticorin race. 
of the type form, T. pirum obtusa. On the east the former race continues as far as 
Talaimannar at the N.W. corner of Mannar Island. A few miles east of this they 
come into contact with the Ceylon form of the type variety. The Kathiawar race 
appears almost identical with the Rameswaram one and may be included with it. 
The approximation may be explained by the fact that the conditions of life in these 
two localities are much the same—the presence of much rocky bottom, and life in a 
sea muddy during much of the year. 
3. Variety comorinensis, var. nov. 
This variety is restricted to the extreme south of the Indian Peninsula; its 
range runs northward from Cape Comorin on both the east and the west coast for 
some 30 to 40 miles. It lives in shallow water exposed to heavy ground swells most 
of the year. The spire is rather short, with a mean index of 83°. The outline in 
axial section is an elongated oval, the body whorl being elongated axially to a con- 
siderable extent (Pl. XI, fig. 9—upper 6 shells). It has the appearance of a stunted 
form of the Tuticorin shell and this was doubtless its origin. It has however developed 
