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



Shell discoid, compressed, the outer whorl embracing the others, so as to leave 

 a very narrow and deep umbiUcus, in which the inner whorls are seen separated 

 by a deep suture. The surface appears to have been smooth. The aperture is 

 oblong and inclined to become triangular ; the angles are rounded off. 



The chambers present four lateral lobes and as many saddles. The superior 

 lateral is very much larger and more divided than any of the others, and extends 

 beyond the dorsal : it is deeply trifurcated and much-denticulated. The dorsal 

 lobe is broad and square, bifurcated at the end, the furcations tridentated and 

 separated by a short square siphonal saddle. The saddles terminate in equal divi- 

 sions, the lobules being more or less phylhform. 



Locality, Pondicherry. A connecting link between the Ligati and Heterophylli. 



17. Ammonites Rouyanus, D'Orbigny. PI. VIII. fig. 6. 



A. Rouyanus, D'Orb. P. F. Ter. Crdt. i. p. 362. pi. 110. fig. 3-5. 



A. testa inflata, laevigata (sub lente striata), umbilico impresso ; anfractibus amplexautibus, 

 convexis ; dorso rotundato, demum striate ; apertura dilatata, rotundata. 



Diameter ly^ inch. 



Diameter of outer whorl 0^^ inch. 



Median thickness of outer whorl . . . 0|^ inch. 



Fragments show that it grows to twice this size. 



Shell resembling a Nautilus in form, smooth to the naked eye. but when ex- 

 amined with a lens seen to be minutely striated ; shining. The umbilicus is im- 

 perforate and impressed. The outer whorl embraces all the others, and gradually 

 increases so as to form a wide, round, trumpet-like mouth. The back is beautifully 

 rounded, and in old specimens is finely striated across. 



Lobes of the sutures very numerous (seven or more), gradually diminishing towards 

 the umbilicus. The lateral ones trifurcated and acutely pinnate. Dorsal lobe as large 

 as the superior lateral, bifurcated, the furcations trifurcated. Intermediate pinnated 

 but unbranched auxiliary lobes between the primary ones. Saddles bifurcated, 

 parts nearly equal and terminating in phylliform lobules. Dorsal saddle as large 

 as the superior lateral lobe. Siphonal inter-saddle small, linguiform. 



Except in the returning whorls of the Indian species being narrower than they 

 are in M, D'Orbigny's figure of A. Rouyanus, I cannot distinguish between them : 

 so prefer identifying the Indian with the French species. The latter is from Cas- 

 tellane. 



Locality, Pondicherry. 



Flexuosi. 



18. Ammonites Egertoni, sp. nov. PI. IX. fig. I. 



A. testa subcompressa, laevigata, transversim radiato-sulcata ; sulcis lateraliter obscuris, ad 



