CEPHALOPODA. 9 



I may mention here that Professor Waagen's fig. l-J is considerably restored; 

 the right upper half is wanting, and the posterior portion of the last whorl is some- 

 what crushed ; the original is therefore by no means so regular as depicted. 



Nautilus intumescbns, Waagen. Plate III, fig. l-la. 



1875. NautUug intumescens, Waagen, PalseontologU Indica. Jurassic Fauna of Kntob Vol I p 20 

 pi. Ill, fig. 3 a-b. • ■ .V . 



Dimensions. 



Diameter of the shell 227 mm 



„ of the umbilicus p 



Height of the last whorl from the umbilical suture ug mm 



» » „ from the preceding whorl .93 



Thickness of the last whorl ]^42 



As will be seen from the above measurements, which represent a shell without 

 body-chamber, this species attains a considerable size. The shell consists of highly 

 inflated, rounded whorls which do not overlap each other completely but leave 

 a comparatively wide umbilicus. Whether the umbilicus was covered by a shelly 

 callosity as in Professor Waagen's original, cannot be decided, the specimen under 

 examination being a cast; it must, however, be stated, that the umbilicus is entirely 

 filled out, but whether by matrix or not, it is impossible to say. The whorls "attain 

 their greatest thickness just above the umbilical edge and slope from there in a 

 gradual curve towards the rounded ventral side. Siphunele sub-central, but some- 

 what nearer the dorsal side. 



Sutural line simple, very slightly cut out on the ventral side. 



Locality and stratigraphical position. — Mazar Drik ; Polt/phemu8-]imeBtone. 



Remarks. — This species is easily distinguishable from the two other forms by its 

 inflated whorls, exhibiting rounded sides and a rounded ventral side. It is by this 

 last feature that this species may be most readily distinguished. 



Although much larger than Professor Waagen's original, I think that the speci- 

 men from Baluchistan must be united with Nautilus intumescens from Kutch. 

 Both forms agree so well as regards the rounded whorls and the generally inflated 

 shape of the shell that I see no reason why they should be considered as different 

 species. The only difference, if difference it can be called, which I can find is that 

 it is impossible to decide whether in the form from Baluchistan the umbilicus was 

 open or covered with a callosity, as it unquestionably was in Nautilus intumescens 

 Waagen. This question must be left open for the present, and unless better pre- 

 served specimens should prove that the umbilicus remained open, this form miist 

 according to the general shape of the shell, be considered as identical with Nautilus 

 intumescens from Kutch. 



Professor Waagen has drawn attention to the close aflBnity between Nautilus 

 intumescens and Nautilus inflatus, d'Orbigny. In this I fully agree with him but 

 I may add that, notwithstanding their great similarity, both forms can be distin- 

 guished by the position of the siphunele. If d'Orbigny's figure exhibits this feature 



