OOLITIC AMMONITES. 
O Q 
QO 
AMMONITES OCTAGONUS.-Shm^,,, MSS. 
Plate 12, figs. 2 a-b. 
A. octagonns, Blanf. Journ. As. Soc., Bengal. 
A. testa discoidea, compressa. Anfr. paullo amplexantibus, sub- 
compressis, ad latera seriebus 3 tuberculorum magnorum ornatis, 
inajquicostatis. Apertura elliptica. Septis lateraliter 3-lobatis 
Diameter of fragmentary whorl 13 in. Spiral ratio .5:3 
Thickness . ,. l'l „ Immersion .£ 
Thickness : diameter.5 
The only specimen of this Ammonite in Colonel Strachey^s 
Collection is a fragment, hut of larger dimensions, and in 
better preservation than that previously described from Spiti; 
and it exhibits characters which lead me to relinquish my former 
idea of its identity with the A. JEugenii of Raspail. The 
fragment in question is a portion of the body whorl (the inner 
whorls being wanting), and is ornamented with three rows of 
very prominent tubercles on each side. The tubercles of the two 
inner series are connected in pairs, by coarse ribs, inclined 
somewhat forwards across the whorls. Those of the outer 
series are connected in like manner with those of the middle 
series, but are more numerous, so that two of the former are 
sometimes connected with one of the middle ones, a character 
not noticed in A. Eugenii. Some of the outer ribs show a 
tendency to a chain-like duplication; but this feature is some¬ 
what exaggerated in the figure. 
AMMONITES HOOKERI.-^rac/^y, MSS. 
Plate 17, figs 1 a-cl. 
A. testa discoidea, umbilicata, tuberculato-costata ; anfractibus 
octagonis. Costis validis, antice arcuatis, apud peripheriam abrupt- 
interruptis ; tuberculis—apud umbilieum lateraque nonnullis mage 
nis; apud peripheriam omnibus compressis; in seric umbilicali pro- 
mineutibus. Costis a tuberculis lateralibus bifurcatis. Umbilico 
aperto. 
Diameter of whorl, 1 inch. Thickness of ditto, 1 inch. 
An opcnly-umbilicatcd shell, ornamented with strong ribs, 
most of which spring from a scries of large tubercles, about 
