CEPHALOPODA. 11 



The sub-globose shell consists of rather low but highly inflated whorls, which 

 exhibit a considerable deviation from the regular spiral line after the shell has 

 attained a certain size. They increase slowly in height and rapidly in thickness 

 apparently, till the beginning of the body-chamber, when they begin to decrease 

 slowly in height but very quickly in thickness, so that the transverse section of the 

 mouth of the shell is much narrower than that of the whorl at the beginning of the 

 body-chamber. The umbilicus is therefore elliptical in cross section, exhibiting an 

 irregular-shaped portion of the preceding whorl. The umbilical wall is rather steep, 

 and the sides pass gradually into the broad rounded siphonal side. The ornament- 

 ation consists of flat rounded ribs, which are single at the umbilical edge and 

 divided into two or three branches on passing over the siphonal side. 



The length of the body -chamber is about three quarters of a whorl. 



Sutural line not visible. 



Locality and stratigrapMcal position. — Sembar Pass ; Polyphemus-\xmG%ioia.Q. 



Remarks. — There is only one specimen from Baluchistan, but ia ornament- 

 ation and "general features of the shell, it bears such a close resemblance to 

 d'Orbigny's figure, that I have not the slightest hesitation in identifying it with the 

 above-quoted species. 



On the other hand, it differs considerably from the Kutch form, which Professor 

 Waagen has named Stephanoceras bullatvm, d'Orbigny. A comparison of the two 

 front views of the Stephanoceras buUatum, from Baluchistan, and Stephanoceras 

 bullafum, Waagen, from Kutch, reveals striking differences. In the first-named 

 species the greatest thickness of the whorls is exhibited at the beginning of the 

 body-chamber, just a little in front of where the aperture rests on it. In the 

 second species (Waagen's fig. 1-6) the centre of the body -chamber approximately 

 marks the greatest thickness. Therefore in Professor Waagen's figure 1-6, two 

 tangents on either side of the last whorl would converge towards the aperture, 

 while in the Baluchistan specimen they would diverge from it. The same differ- 

 ence exists between d'Orbigny's original of Ammonites bullatus and Professor 

 Waagen's Stephanoceras bullatvm from Kutch. Professer Waagen has apparently 

 noticed this difference, for he says : " though I am not sure if the specimens figured 

 by Quenstedt and Gemmellaro, with which the Indian form principally agrees, 

 are in reality the same species as that which was understood by d'Orbigny to be 

 Ammonites bullatus, yet I cannot make a distinction." 



If, however, the specimen from Kutch is compared with that from Baluchistdn 

 it is obvious that the two forms cannot be considered as representing the same 

 species. On the other hand, the species from Baluchistan agrees with regard to the 

 abovementioned feature much more with d'Orbigny's Ammonites bullatus than does 

 the specimen from Kutch. I think that it would have been preferable to give the 

 latter a new name instead of identifying it t^ith a form from which it is dis^ 

 tinguished by such marked features. 



In the absence of sufficient material I do not intend to attempt to decide the 

 question as to whether Quenstedt's Amm,onUe8 bullatus is in reality identical with 



