58 
Records of the Geological Survey of Lidia. 
[vox,. i. 
Of these 30 identical species, forming very nearly one-eighth of the entire fauna, 10 species 
occur in the Senonien, 12 in the Turonien, 4 in the Cenomanien (including 2 species from the 
South African deposits); 1 species is common to the first and second, 1 to the second and third, 
and 3 are quoted from the Gault, 2 of which, however, are also found in the Cenomanien. 
Applying these results in detail to the groups distinguished by Mr. Blanford among the 
South Indian cretaceous deposits, it will be found that they do not correspond exactly. 
Thus, species which in Europe occur in the Cenomanien are in India occasionally found 
in the Arrialoor beds, not as would be expected in the Ootatoor beds only ; and again there 
are Senonien and Turonien species found in the Ootatoor as well as in the Tricliinopoly 
beds. As a rule most of the speeies from our Arrialoor beds arc identical with those from 
the Senonien; but there appears to be au equal difficulty experienced in India in separating 
the Arrialoor and the Triehinopoly group, as is felt in Europe in distinguishing properly 
between the Senonien and the Turonien. The general conclusion, therefore, derivable from 
the examination of the Gastropoda regarding the age of the South Indian cretaceous 
deposits is that they represent only the beds above the Gault, that is, the Cenomanien, 
Turonien ancl Senonien. 
It is possible that the Ootatoor beds represent the Cenomanien, hut the number 
of fossils obtained from these beds is, in one respect, comparatively as yet very small; 
in other respects the boundaries between this and the other groups may not have been suffi¬ 
ciently worked out. It appears more justifiable to regard the Tricliinopoly beds as the 
representatives of the Turonien, and (as already stated) the Arrialoor as those of the 
Senonien. Stratigrapbieally this tri-division has also great probability. 
When reviewing the Cephalopoda of the same rocks (Quart. Jour., Geol. Soc., Lond., 
1865, p. 407, etc.), I have stated that the largest number of the identical species of 
Cephalopoda occurs in Europe in the middle cretaceous strata and especially in the 
Gault; thus I placed the lowest beds of our South Indian cretaceous rocks as equivalents 
of the Gault. After having gone over the Gastropoda I found that no Gault species 
were represented, and conferring with some of my friends at home on this point, Prof. Hebert 
specially directed my attention to several species of the Cephalopoda which are strictly 
speaking not typical Gault fossils. I had already occasion to mention* that the identification of 
Am. Beudanti (now Am. Yama, Forb.) was found incorrect; hut several other species which 
undoubtedly appear to be identical with European fossils, like Nautilus elegam, N. sullerri- 
gatus, Am. restrains. Am. Rotomagensis, Am. Candollianvs, Ain. iiavieuldris, Am. 
Mantelli, Am. peramplus, Am. Timothcanus and laiidormlus, TnrriUf.es costatus and 
Bergen and others, are such species as pass from the Gault into the Cenomanien and the Gres 
verts, Prof. Hebertf is of opinion that the true Gault beds must be considered as the upper¬ 
most group of the Ncocomien or lower cretaceous series, all the beds above being included in 
the upper cretaceous series. There appears to he a relation of several of our species to 
such Gault species as Am. Beudanti, serratus, lautus, denarius, splendens and to some 
Neooomien forms, but, on the other hand, the numerous Cristati and Ligaii of our rocks 
are strongly marked upper cretaceous types. The fauna of the Gault is undoubtedly an 
intermediate one, and possibly when the stratigraphy of the rocks has been better studied 
many corrections in points of identifications, at pi-esent doubtful, may be made. Some of 
the species like Nautilus pseudo-elegans and Neocomiensis, and Am. Rouyanus and 
Velledte I am still unable to distinguish satisfactorily from the typical Neooomien species; 
the number of these species is, however, so small that they cannot outweigh the other facts 
which would place the cretaceous deposits of South India higher in the series. 
Considering, therefore, that most of the so-called Gault speeies of our Cephalopoda are 
equally comnmu in the Cenomanien, and that the Gastropoda have not yielded any undoubted 
Gault forms, I believe I am more justified in stating that the South Indian cretaceous 
deposits only represent the upper cretaceous strata, beginning with the Cenomanien. The 
larger number of representative species were found to agree with the Turonien, which 
is a very wide spread formation, though its limits must he considered rather different from 
those given to it by d’Orbigny. I have reason to suppose that the present statement regard¬ 
ing the age of our cretaceous deposits will also be supported by the examination of the 
* Records Geol. Snrv., India, 1. pt. 2,1868, p. 35. 
t Bull. Soc. Geol., France, 2d ser., t. XXIV, p. 323, etc. 
