1844.] 393 



9. Ammonites Hopkinsi. Nov. sp. 



a. Side view, showing the outline complete and a portion of the shell. 



b. View showing the lobes in the septa. 



A. testa crassd, umbilicatd, transversim sulcata costatdque ; sulcis 6, suhundu- 

 latis, marginatis ; dorso rotundato, transversa costatoj costis inter sulcos 5—S, 

 rotundatis, lateraliter obsoletis ; aperturd ovato-lunatd ; septis—. 

 Diam. 21. Crass. 1-^ unc. 



This fine Ammonite has an inflated shell, which appears to have been of 

 considerable thickness. The outer whorl does not entirely conceal the 

 others, but leaves a deep umbilicus which in the perfect shell probably ex- 

 posed several of the inner volutions. The sides of the whorls forming the 

 boundary of the umbilicus are steep, in consequence of sudden inflections 

 of the shell. The middle of the whorls is flat and nearly smooth ; the back 

 is rounded, and transversely sulcated, with rather broad, slightly undulated 

 shallow furrows, which are separated into groups of from five to eight by 

 distant, wider, and deeper furrows, which run in a curved manner entirely 

 across the whorls. These sulcations, marking stages of growth, are very 

 stron«' on the cast, but comparatively slightly marked on the external sur- 

 face of the shell, showing that they are the marks of internal ribs. The 

 mouth appears to have been lunate, and slightly elongate. It belongs to the 

 section Ligati. It is very nearly allied to an Ammonite from the lower 

 greensand of Southern India. 

 10. Ammonites Inca. Nov. sp. 



A. testd crassd, umbilicatd, radiato-striatd, sulcata; sulcis undulatis 6 ; dorso 

 rotundato ; aperturd lunatd, laid ; septis pinnatis, multilobatis. 



Med. semi-diam. 1^. Ult. anf. 1^^. Crass. 1^ unc. 



This species is nearly allied to the last, and resembles it in form, but 

 differs in the absence of smaller sulcations between the greater furrows, 

 which divide the cast of the outer whorl into six wide divisions, and which 

 on the external surface of the shell were marked by raised ribs. These 

 furrows and ribs proceed in an undulate and rotate manner from the umbi- 

 licus which appears to have partially exposed the inner whorls. The sur- 



G G 4 



