OF SOUTHERN INDIA. 215 
Mathilda,* although we could not pronounce a definite opinion as to whether 
the genus will stand as proposed by Mr. Semper. The Zwrritella Bonei, Baily, 
(Quart. Journ. Geol. Soc., Lond., XI, p. 455, pl. 12, fig. 7, not 7. Bouei apud 
Pictet et Campiche) from South Africa could possibly be a Mathilda, but it would 
be a gigantic species of this genus. Several tertiary and recent species were des- 
cribed by Semper. The cancellated species of Mathilda would form a passage to 
the next family, the Scazrpm. 
XLVII.—ARCOTIA, Stoliczka, 1868. 
1. ARcorra Inpica, Séoliczka. Pl. XVI, Fig. 12, and Pl. XIX, Fig. 6. 
Are. testa turrita, crassa; anfractibus antice bicarinatis, (carina anteriori multo 
tenwiori, postica acute elevata), marginem posteriorem versus gradatim angustioribus, 
striis tribus fortioribus atque multis minoribus ornatis ; striis incrementi minutis, rectis : 
basi ultimi anfractus valde convexa atque spiraliter striata ; columella late excavata ; 
apertura intus valide angulata ; labio levigato, moderate incrassato. 
Spiral angle 35°- 38°; sutural angle 8°- 9°. 
Height of last whorl : total of shell (consd. as 1:00) od vv =0°33. 
Height of penultimate whorl : height of spire (consd.as 1:00) ... 0°24. 
se 3 nA oh : its width (consd. as 1:00) ... we =O'44. 
The conical form of the shell, the double keel along the anterior margin, and 
the gradual posterior tapering of the whorls, as well as the strong convexity of the 
basis of the last volution, are very distinctive characters of this species. There are 
generally three thicker spiral lines, of which the one next to the strong keel is 
thinner than the two others. In younger specimens this third thinner keel is often 
not very clearly traceable, while in larger specimens a fourth one attains occasion- 
ally a nearly equal strength. Besides there is a large number of finer spiral 
strize present, all of them crossed by the straight transverse lines of growth. The 
aperture is rather distinctly angular on the columellar side, and more uniformly 
roundish on the outer lip. The inner lip is smooth, and like the rest of the shell 
of considerable thickness. A 
Coquand describes from Epagnac a Turr. wmbilicata, (Bull. Soc. Géol. France, 
1859, Vol. XVI, p. 979) with narrow and smooth whorls, and a large umbilicus; 
the short description would rather apply to a Niso. 
Locality North of Alundanapooram, in greyish sandstones; apparently 
rather rare. 
Formation.—Trichinopoly group. 
* Conrad (Smithsonian Mise. coll.; Check list inv. foss., eocene, 1866, p.14,) places the genus in the 
CE RITHIOPSIDE. 
