104 Prof. E. Forbes on Fossil Invertehrata from Southern India. 



Diameter lj% inch. 



Diameter of outer whorl Oy^ inch. 



Breadth Oj% inch. 



Shell discoid, the whorls ornamented with obsolete ribs on their inner sides, 

 forming elongated tubercles immediately over the deep and steep-sided umbilicus. 

 The whorls are five in all, the outermost broader than all the rest together. The 

 aperture is kidney-shaped and inclined to triangular. 



The chambers are complicated. The lateral lobes are three or four in number, 

 much-divided, and more or less trifurcated. The dorsal lobe is nearly as long as 

 the superior lateral, deeply divided, and sends out two narrow trifurcated branches 

 which are separated by a quadrangular, oblong, siphonal saddle. The saddles are 

 bifurcated, their branches narrow, deeply separated and much-ramified. 



Locality, Pondicherry. 



An abnormal form of the section Ligati, approaching nearest a group of gault 

 and upper greensand forms of which the Ammonites peramplus of Mantell is an 

 example. 



9. Ammonites Cala, sp. nov. PI. VIII. fig. 4. 



A. testa discoidea, laevigata, anfractibus 6^ rotundatis ; umbilico lato ; dorso rotundato ; aper- 

 tura reniformi. 



Diameter ly'^ inch. 



Diameter of outer whorl Oyt^ inch. 



Thickness .......... Oy^^ inch. 



Shell resembling in shape Planorbis corneus. The whorls are six, and exposed 

 in the wide and shallow umbihcus. The mouth is wide in consequence of the dila- 

 tation of the outer whorl. 



Chambers with many-lobed partitions. Lobes five or six, more or less tri- 

 furcated, rather short, rapidly decreasing towards the umbilicus, and placed in an 

 oblique line. Dorsal lobe large, much pinnate and bifurcate, exceeding the superior 

 lateral. Saddles bifurcated and more or less phylliform in their extreme divisions, 

 equalling the lobes in dimensions, and gradually decreasing towards the umbilicus. 



This species is nearly allied to the French Neocomian form, Ammonites Emerici. 

 It differs however in the absence of distant sulcations, a character which would 

 separate it from the group Ligati were it not so very near in all other respects 

 several species of that section, and in the size of the dorsal lobe and number of the 

 lateral ones ; the former being much larger in proportion to the superior lateral, 

 and the number of the latter being fewer than in A. Emerici. 



10. Ammonites Durga, sp. nov. PI. VII. fig. 11. 



A. testa discoidea, laevigata, compressa, anfractibus 4, planis, suturis profundis, dorso ro- 

 tundato, corapresso; apertura lanceolato-ovat^. 



