CEPHALOPODA. 19 



low and rounded. The flat sides gradually slope towards the rounded siphonal side. 

 There are about four not very distinct contractions to one volution. The whorls are 

 covered with straight rounded ribs, which begin at the umbilical edge and ex- 

 tend to about half the height of the whorl, where they split up into three finer 

 branches, which pass in a straight line round the siphonal side. Neither body- 

 chamber nor sutural lines to be seen. 



Locality and stratigraphical position. — Mazdr Drik ; Polyphemus-liraestone. 



Remarhs. — This species is fairly common at Mazar Drik, although none of the 

 specimens are particularly well preserved. However, as I could compare them with 

 Professor "Waagen's original of Perisphinctes balinSnsis, I was enabled to establish 

 their identity with that form, which is characterized by its very e volute shell and 

 the straight ribs, which are fairly strong near the umbilical edge, but gradually 

 become thinner before they branch into the regular thin ribs, which pass round the 

 siphonal side. I have therefore no doubt that the Baluchistan specimens represent 

 the same form as those from Kutch, but I cannot quite agree with Professor Waageh, 

 who is of opinion that the latter are identical with Neumayr's Perisphinctes 

 balinensis. It seems to me that Perisphinctes halinensis, Waagen, differs from 

 Perisphinctes balinensis, Neumayr, by a much more evolute shell and consequently 

 a wider umbilicus, which allows of the exposure of a larger number of whorls, a 

 feature which will be at once noticed when comparing the figures of the two authors. 

 I am rather inclined to think that Perisphinctes balinensis, Waagen, bears a much 

 closer relationship to Perisphinctes furcula, Neumayr, than to the P. balinensis 

 of that author. In both forms we have the same evolute shell, and, what is more, 

 the character of the ribs is the same, inasmuch as the primary ribs split up into 

 three finer branches. It must, however, be noted that the smaller specimens from 

 Baluchistan show that on the earlier whorls the ribs frequently divide into two 

 branches, a character which was probably unnoticed by Neumayr owing to the fact 

 that the point where the primary ribs divide is hidden in the iuner whorls and only 

 two specimens were available for examination. 



Although I am, therefore, of the opinion that Prof essor Waagen's Perisphinctes 

 balinensis would have been better identified with Neumayr's Perisphinctesfurcula, 

 I retain Professor Waagen's determination, for I think that this question can only 

 be settled by actual comparison of the type specimens. On the other hand, it must 

 be understood that, whatever the specific name of Perisphinctes balinensis, Waagen, 

 nlay be, that form is identical with the Baluchistan specimens which have been 

 here described. 



PeEISPHINCTBS BALTJCHISTANBNSIS spec. NOV. PI. XIII, fig. 2.2a, fig. 3. 



Dimensions. 



82 ^\ 



Diameter of the shell 35 29 



„ of the nmbilicuB 9!; 94, 



Height of the last whorl from the umbilical suture Z, p 



„ from the preceding whorl ' ' * ' ] ^ J^ 



Thickness of the last whorl 



