CEPHALOPODA. 15 



collection of the Geological Survey Museum, the only specimen there preserved 

 being that from which the sutural line, fig. 2, has been figured. But this specimen 

 differs so entirely as regards the shape of the shell from that figured on Plate 

 XXIX, fig. la, lb, that I am at a loss to understand how these two specimens could 

 have been referred to one and the same species. The section of the whorls is not 

 approximately square as in the former, but is elliptical, and the overlap of the 

 whorls is too pronounced to accord with Professor Waagen's figure. The umbilicus 

 is therefore much narrower than is represented in fig. la. 



As the original of fig. la and 16 cannot be traced, and has apparently been lost, 

 it is impossible to say how far fig, la and 16, which are drawn to half the natural 

 scale, represent its features ; we must therefore fall back on the specimen from which 

 the sutural line has been figured if we wish to study the features of the Stephanoceras 

 polyphemus, and for this purpose I give a figure of this specimen, PI. XII, fig. 1 

 and 2, from which its difference from Waagen's fig. la and 26 will be apparent. 



Under these circumstances I think 1 am justified in retaining the specific name 

 "polyphemus" for the form from which the sutural line has been figured, and in 

 discarding Waagen's fig. la and 16 altogether. Should it, however, be found again, 

 or should new specimens be found which answer to that figure, and could it there- 

 fore be proved that the figure is really correct, that form might receive a new name. 

 If, on the other hand, by means of the original or other specimens, it could be 

 proved that the figure is incorrect, the above arguments would hold good. As 

 regards ornamentation and shape of the shell the specimens from Baluchistan agree 

 so well with the specimen from which the sutural line has been figured, that they 

 must be considered as identical with that form. On the other hand, they are 

 entirely different from Waagen's fig. la and 16 of Stephanoceras polyphemua. 



Macbocephalites stjbcompresstjs, Waagen. PI. IX., fig, 2. 



1875. Stephanoceras suhcompressum, Waagen, Palsontologia Indica, Jurassic Fauna of Kutoh, Vol. I, p. 

 139, PI. XXXIV, fig. la. 6, 



None of the specimens under examination are sufficiently well-preserved to 

 allow of accurate measurements being taken, but it seems that this form attained 

 only moderate dimensions, the largest specimen being probably not more than 

 110""" in diameter. The whorls are high and laterally compressed, considerably 

 overlapping each other; umbilicus tolerably wide. The sides are covered with very 

 equal, sharp ribs which rise at the umbilical edge. They are slightly bent forward, 

 and at about the middle of the height of the whorl they generaUy bifurcate ; some- 

 times a secondary rib is intercalated between two primary ones, approximately 

 taking its origin at their point of bifurcation. All the ribs are of equal strength, 

 more proniinent on the siphonal portion than on the sides, and follow each other at 

 equal intervals. On the siphonal side the ribs are still more bent forward than 

 on the sides. Neither body-chamber nor sutural line can be observed. 



Locality and stratigrapUcal position.— Maziv Drik ; Polyphemus-limestone. 



J?e»w«r;fcs.— According to Professor Waag6n this species is easily distinguished 



