100 Prof. E. Forbes on Fossil Invertebrata from Southern India. 



Fimbriati. 

 1. Ammonites Vishnu, nov. sp. PI. VII. fig. 9. 



A. testa compressa, laevigata, transversim costata, costis simplicibus, distantibus, prominenti- 

 bus ; dorso rotundato ; apertura ovato-cordata. 



Diameter, 4;^ inches. 



Diameter of disc formed by the inner whorls, 2 inches. 



Medium thickness of outer whorl, 1 inch. 



Whorls five or six, rounded, forming a concave disc, which however is not deep in 

 the centre. Each whorl is banded at intervals by strong rounded ribs, those towards 

 the mouth on the outermost whorl becoming fewer and more distant, and present- 

 ing the character of oral varices. There are fifteen on the outer whorl. The 

 surface of the shell appears to have been smooth. The mouth is broadly ovato- 

 cordate. The sutures are plainly seen on the second volution. The young shell 

 was probably ribless. 



In the specimen figured, the sutures of the chambers are visible only on the 

 exposed portion of the second whorl. The lateral lobes are pinnate and bifurcate, 

 and appear to have been three or four in number. Their relative arrangement is 

 not exposed. 



The cast is deeply furrowed in the region of each varicose rib, and undulated 

 beneath the intermediate ribs. 



This species approaches very nearly the Neocomian Ammonites honor atissimus of 

 M. D'Orbigny (Ter. Cret. i. plate 37), It differs in being less compressed ; in 

 having more numerous transverse ribs, especially on the second whorl ; and in the 

 form of the aperture, which in the French species is oblongo-ovate. 



Locality y Pondicherry. 



2. Ammonites Brahma, nov. sp. PI. VIII. fig. 1. 



A. testa compressa, laevigata, transversim sulcata costataque ; sulcis marginatis distantibus, 

 costis numerosis lateraliter obsoletis ; anfractibus sex, internis acute, tuberculatis ; dorso rotun- 

 dato ; apertura reniformi. 



Diameter 4 inches. 



Diameter of inner whorls 2 inches. 



Median breadth of outer whorl . . . 1^ inch. 



Shell compressed ; whorls six, smooth, convex, the outermost transversely sul- 

 cated and strongly ribbed at intervals ; the strong ribs six or seven in number, the 

 intermediate ones continuous over the rounded back, but obsolete at the sides: 

 the inner whorls with fewer sulcations, but ornamented with acute tubercles ; the 

 umbilicus is rather deep ; the aperture is transversely reniform. Young shells 



