'igs. 1 — 23. 
PLATE VI. 
Thi!ebratui.a subrotunda, Soicerhy, j-). 22. 
Figs. 1-6 represent specimens in diirerent stages of age of tlie rounded variety, with 
a moderately large aperture of the beak and almost entire absence of a frontal 
sinus ; fig. 5 is from Ead of Andoor, and the other five sj)ecimeus from near 
Karapmdy, Arrialoor group. 
Figs. 7-16 represent more ovate shells, in most of which a slight frontal biplication 
of the margins is indicated ; the aperture of the beak is of the same size as in 
the round variety; fig. 7 is from near Karapaudy ; fig. 11, which represents the 
brachial apparatus, and 11«, the impressions of the muscular scars of the htemal 
valve, are taken from a Feraghoor specimen ; the other larger specimens are all 
from S. IF. of MuUoor ; Arrialoor group. 
Figs. 17-23 represent specimens of the variety sulmndaia, most of them having a 
remarkably small opening in the beak of the neural valve; 17 is an abnormal 
specimen of a transversely ovate shape, the front having at one time evidently 
been injured; from S. E. of Karapaudy, Arrialoor group. Fig. 18 shows the 
normal form of the small beak, and, like fig. 19, is from Shalanure; the remaining 
figures are taken from specimens found between Andoor and Feraghoor ; Trichi- 
nopoly group. 
