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



the ribs, sometimes entirely and sometimes only imperfectly. Sulcations of the 

 sides twice as broad as the simple and prominent ribs. 

 Locality, Pondicherry. 



7. Hamites undulatus, sp. nov. PI. X. fig. 6. 

 H. testa tereti, elongata, arcuata, transverse costis obscuris undulata. 

 Circumference of largest specimen Oy'^ inch. 



A very slender pipe-like species, distinguished from all the others by its round, 

 smooth, undulated surface. 

 Locality, Pondicherry. 



Genus Ptychoceras, D'Orbigny. 



Of a species of this interesting and curious genus, established by M. A. D'Orbigny, 

 there are numerous fragments, beautifully preserved, in the Pondicherry collections. 

 The known European species of Ptychoceras are from the lowest beds of the Cre- 

 taceous system. 



Ptychoceras sipho, sp. nov. PI. XL fig. 5. 



P. testa elongata, laevigata, undulato-plicata ; plicis prope aperturam frequentioribus. 



Length of longest specimen 4 inches. 



Median circumference H inch. 



The shell is round, straight for the greater part of its length, and tapers poste- 

 riorly ; at its widest part it makes a sudden crook-like curve to form the aperture. 

 This portion is more frequently plicated, and the plications stronger than at the 

 straight portion ; posteriorly it seems to have made a similar sudden curve ; in the 

 younger specimens, indeed, so sudden, that the two parts of the crook are touch- 

 ing. The bend below is striated transversely. The nature of the final termination 

 has not been seen. 



The chambers present six lobes and six saddles comparatively (with Hamites) 

 very simple, and not diflfering very greatly in size. The dorsal and ventral lobes 

 are largest. The dorsal, as well as the laterals (which are equal), are bifurcated, 

 each furcation slightly bidentate ; the ventral is trifurcate. The saddles are broader 

 than the lobes, and composed of two nearly equal, broad, emarginate (bi-lobuled) 

 branches. 



Locality, Pondicherry. 



Genus Belemnites, Lamarck. 



Of this genus there are in the Pondicherry collection, — 



1. The chambers and part of the sheath of a middle-sized conical species, but 

 indeterminable. The nucleus is represented in PI. IX. fig. 4. 



