68 Transactions of the Boyal Society of South Africa. 
Observations. — With the exception of dental and other internal 
characters, which are not displayed, the specimens referred to this 
species conform in every way externally to the shell originally de- 
scribed and figured by Stoliczka as a characteristic member of the 
Trichinopoly fauna of Southern India. Its ornamentation and con- 
tour distinguish it from other forms of the genus, being trapezoidal 
having strongly incurved anterior umbones excavated beneath 
to form the lunule, and a prominently arched carina extending from 
the umbo to the postero-ventral angle, which encloses the abrupt, 
deep, medianly inflated posterior area. The sculpture consists on 
the anterior side of equidistant, concentric, elevated laminae, divided 
by finely striated, shallow sulcations of nearly equal width through- 
out ; the surface of the posterior region shows a central ridge-like 
elevation emanating from the umbo and running parallel with the 
curved carina, which becomes more or less obscured as it extends in 
the infero-posterior direction ; and in addition the surface of the area 
is ornamented with an unbroken series of closely arranged oblique 
striations. 
Among the examples of this species four represent a medium, 
and one an adult growth, the latter being in a fine state of preser- 
vation, possessing both valves in the closed condition, and which, 
moreover, are properly in situ. It is only right to mention that 
this specimen was skilfully denuded of its matrix by Mr, C. P. 
Chatwin, of the Geological Department of the British Museum ; 
except that it is rather less in size this specimen agrees in every 
detail with the Indian form represented on Stoliczka's pi. 9, 
figs. 6-6c ; associated with it was the convex valve of Neithea 
quinqiiecostata. 
Dimensions (adult specimen with both valves). — 
Length 62 mm. 
Height 70 ,, 
Diameter 55 ,, 
The maximum length of the Indian shell is given as 75 mm. 
According to Stoliczka (Cretaceous Pelecypoda, Southern India, 
Fal. Indica, 1865, p. 90) Ammonites tamulicus of Blanford occurs in 
the Trichinopoly group of different Southern Indian locahties, 
similar places being given by the same author for Cyj^rina 
forhesiana. Such beds are regarded by Kossmat as of Lower 
Senonian age or the upper part of the Trichinopoly series (see 
Becords GeoL Surv. India, 1897, vol. 30, p. 82— Correlation Table), 
the Cephalopod being now recognised by that author as Placenti- 
ceras tamulicum [Beitr. Pal. Geol. Osterr. — Ungarns, 1895, vol. 9, 
parts 3 and 4, p. 174). 
