14 JURASSIC PAUNA. 



part of the last whorl a considerable piece has been broken off in the original, the ribs 

 being almost completely effaced. As regards the front view (2i) it must be stated (1) 

 that the fine sharp cross-section of the last whorl is entirely wanting in the original, 

 in fact it is wholly imaginary, and (2) that the siphonal view of the posterior part of 

 the last whorl is equally imaginary, inasmuch as in the original a large part of the 

 right-hand side is broken away, so that the siphonal lobe of the septum is exposed. 

 I regret the necessity for such strong criticism, but in support of the above state- 

 ments I give here a figure of Professor Waagen's original Stephanoceras transiens as 

 it really appears in order to facilitate a comparison between the restored figure and 

 the type specimen. 



Maceocephalitbs poltphbmtjs, Waagen. PI. XI, fig. 1-la. 



1875. Slephanoceras polyphemtis, Waagen, Falaeontologia Indies, Jarassio Fauna of Eutoh, Vol. I, p, 116, 

 PI. XXIX, fig. 2 (non fig. la, IJ !) 



Dimensions. 

 Diameter of tlie shell 



„ of tbe umbilicus .... 



Height of the last whoil from the nmbilical sutuie 



„ ,, „ „, „ from the preceding whorl 

 Thickness of the last whorl .... 



The shell consists of inflated but rather low whorls which overlap each other 

 so completely that the umbilicus becomes very narrow. The sides are rounded, and 

 gradually slope from the umbilical edge towards the rounded siphonal side. The 

 ornamentation consists of strong ribs which begin at the umbilical edge and divide 

 at a short distance above it into three or four branches which are very regular in 

 thickness, equidistant, and pass round the siphonal side, where they attain their 

 greatest developiaent. 



Body* chamber, about |- of the entire whorl. 



Sutural line only indistinctly seen. 



Locality and stratigraphical position. — Mazar Drik; Folypliemus-Mme&ione. 



Remarks. — This species is easily distinguished from the others by its low inflated 

 whorls, and the rather coarse ribs, which subdivide close to the umbilical edge, 

 but it is a noticeable fact that they become entirely effaced on the enormous speci- 

 mens, such as No. 1. This species is rather common in Baluchistan, where it attains 

 dimensions which according to Mr. Griesbaeh are even greater than those of No. 1, 

 of which the measurements are given above. 



* I bad some difl&culty in identifying this species, as it is not quite certain what 

 form really represents Stephanoceras polt/phemm, Waagen. According to Professor 

 Waagen's figure 2a and 26 the shell of Stephanoceras polyphemus consists of lo^' 

 whorls which are approximately square in cross-section. If fig. 16 may be relied 

 upon it was not very involute, and fig. la distinctly shows that the umbilicus was not 

 very narrow. Unfortunately the specimen referred to could not be found in the 



