90 
Records of the Geological Survey of India. 
[vOL. [V, 
ave never tripartite on the outer margin, but sometimes bipartite and sometimes cross undi¬ 
vided over the siphonal side. 
Perisphinctes aberrans, Waagen, n. sp. The only species with which I can compare 
this form is Per. Albcrtinus, Cat., hut the dillcrence lies in Catullo’s species possessing a 
furrow on the siphonal side when young, while there is no trace of it in the present species. 
The dissimilarity, however, between young and old specimens of aberrans is by no means 
less marked than in Per. Albertinus. The young form resembles a little Per. 'eonvolutus ; 
it has many separate rounded whorls, with fine ribs and tolerably numerous very oblique 
contractions of the whorls. When growing larger the ribs of the individual become in an 
equal degree more distant, stronger and higher on the sides of the whorls, whilst, on the 
contrary, they gradually disappear on the siphonal side. 
The third section (of Per. plicatilis, Sow.) is the richest in forms in the whole Jura. 
In Europe it is represented by at least 100 species, all occurring in strata of Oxfordian, 
Kimmeridgian or Tithonian age, but for the greater part the species are as yet undes- 
cribed. The difficulty, therefore, not only in determining, hut in comparing the Indian 
species with European forms, is much greater in this section than in any other, and the con¬ 
clusions, which in other groups and genera are so naturally associated merely with their 
names, can in this instance not be drawn from the identity of the species, hut only from the 
general habitus of the forms; however, some of the Indian species can nevertheless be 
identified with European Ammonites. The species belonging to this section are : 
Perisphinctes Indogermaims, Waagen, n. sp. (brown oolite, Jooria hills; yellow 
marl rock, Joorun). 
„ plicatilis, Sow. (red iron rock of Kuntkote; same rock at Joorun). 
„ torquatus, Sow. (coarse iron sandstone of the Katrol range). 
„ bathyplocus, Waagen, n. sp. (same layer and locality). 
„ Poftingeri, Sow. (same layer and locality). 
„ euplocus, Waagen, n. sp. (same layer and locality). 
„ Katrolensis, Waagen, n. sp. (same layer and locality). 
„ virguloides, Waagen, n. sp. (red iron rock of Kuntkote). 
Perisphinctes Indogermanns, Waagen, u. sp. Very nearly allied to Per. plicatilis, 
Sow., and often mistaken for this species, hut, distinct from it by rounded whorls and flat¬ 
tened ribs on the siphonal side. There are specimens in our museum from Kutch as well as 
from Trouville in Normandy (Zone of Am. cordatus). 
Perisphinctes bathyplocus, Waagen, n. ,sp. Allied to Per. torquatus, Sow., so much 
so that young specimens are almost umlistinguishable. Per. bathyplocus has, however, 
always finer ribs and thicker whorls. When large, the lateral parts of the ribs are much 
swollen and distant from each other, and to each of them correspond five or six fine ribs on 
the siphonal side; only in very large specimens the latter become obsolete, or very nearly 
so. 
Perisphinctes euplocus, Waagen, n. sp. Allied to Per. Poftingeri, Sow., hut with 
much thinner whorls, and S-shaped, irregular, fiue ribs. On the body-chamber the ribs 
become scarcer, more prominent and straight. 
Perisphinctes Katrolensis, Waagen, n, sp. Equally allied to Per. Poftingeri as the 
last, hut attaining a much larger size, and with the body-chamber much less strongly ribbed. 
Perisphinctes virguloides, Waagen, n. sp. Closely resembles Per. virgulatus, Quenst; 
the ribs are, however, not so fine and the contractions of the shell indistinct. 
The next species belongs to a group which is of great importance for the geology of the 
European Jura : it is— 
Perisphinctes leiocymon, Waagen, n. sp. (red iron rock of Kuntkote). 
