PAllT 4 .] 
187 
Foote: Geology of North Arcot Didrict. 
as not an over estimate of the dimensions of the fully adult animal, whieh pro¬ 
bably exceeded the dimensions of the largest CMtra, though our positive knowledge 
of the precise limits attained by our living Chclonian is singularly meagre and 
limited. That Gautleyawas an aquatic species may be inferred from the cartilaginous 
union of the bones of its case, which in living species is seen in such fluviatile forms 
as Guora and Gijdemys and is unknown in terrestrial forms. The opposite ex¬ 
clusion, however, among Chclonia cannot be dra^vn from the complete ossification 
of the body case, as Batagur and its allies are possessed of as completely ossified a 
case, though strictly aquatic, as Testudo, which is entirely terrestrial. 
The specimen was obtained near Nila, on the Sohan river, in the Rawal¬ 
pindi district, in upper Siwalik strata, and in company with remains of Mastodon 
perimensis, F. et C., M. pandioms, F., Piilceopitliecus sivaleusis, Lyd., Aoerwtheiiwn 
perimense, F. et C., and other Siwalik fossils. 
Among the collection from the same locality are fragments of a largo Testu- 
dine, exceeding in size the living Mcinouria. They consist of one anchylosed 
pair of episternal bones, with a transverse diameter of S'S inches (allowing for 
a slight fracture) ; a single right episternal bone of a rather larger size, 2'5 inches 
thick and 6-25 long, and a free marginal (that is, one anchylosed to the thorax 
only) 3-8 broad and 4-6long (measuring from the outer margin). 
These bones would indicate an animal nearly as large as the last, and probably 
fully equal to it in bulk. At present, howmver (with no other materials), it seems 
undesirable to give it a name. 
Sketch of the Geology of North Arcot District, ly R. Bruce Foote, F.G.S., 
Geological Survey of India. 
The North Arcot District, one of the purely inland districts of the Madras 
Presidency, is topographically characterized by its great 
Topography. irregularity of surface. Except in its south-eastern 
quarter, the district is extremely hilly and in some parts quite mountainous. In 
the west and north-west it embraces a considerable part of the high and rugged 
eastern scarp of the great Mysore plateau, from which many long spurs jut out 
far to the eastw'ard. In the south-west it includes the northern end of the 
Javadi mountains and the Vellore hills. In the north it includes the W'ell known 
Tripatti mountains, the “ sacred hills of Trippetty,” and the southern extremity 
of the Vcllakonda (Eastern GhMs so-called). The north-eastern corner of the 
district contains the Nagari mountains; and three gi-oups of low^er hills, the 
Sattavedu, Alikur, and Naikenpalem hills, on the extreme eastern border of the 
district, and a considerable number of detached hills in the gneissie country west 
of the Madi-as railway. Some of these latter, as the Maddur (Jluddoor), Sholin- 
ghur, and Makrs Drug hills, and others, are of considerable height and extent. 
In the south-east of the district only two detached hills need be named, those of 
Wandiwash and Chitpat (Ohittapett). 
