CEPHALOPODA. 13 



width of the umbilicus, but particularly the character of the fine and regular ribs 

 which die out towards the umbilical edge, agree so well in both forms that I do not 

 think that the difference noted above justifies a specific separation. 



Professor Waagen has so clearly indicated the characters by which Macrocepha- 

 Utes macrooephalus differs from related forms, such as Macrocephaliies tumidua 

 or Macroeephalites transiena, that nothing more can be added. 



Macrocephalites transiens, Waagen sp. PI. X, fig. 2. 



1871. Stephanoceras macrocephalum (Sclil.) Waagen : Eecords, Geol. Surv. of India, 1871, p. 93 (pars.) 

 1875. Stephanoceras transiens, Waagen, Palseontologia Indioa, Jurassic Fauna of Kutoh, Vol. I, p. Ill, 

 PL XXXII., fig. 2 a, b. 3. a, b. 



Measnrements. 



Diameter of the shell 165 mm. 



„ of the umbilicQB ........ 20 „ 



Height of the last whorl from the nmbilical suture .... 86 „ 



„ „ „ from the preceding whorl ... 65 „ 



The shell is discoidal, the whorls overlapping each other almost entirely, so that 

 a very narrow umbilicus is formed. The sides of the whorls are fl,attened and slope 

 very slightly from the rounded umbilical edge towards the rounded umbilical side. 

 The thickness of the whorls being considerably less than their height, and the cross - 

 section is therefore of the form of an ellipse with a long vertical axis. 



The ornamentation consists of numerous low rounded ribs, which begin on the 

 umbilical wall and extend to about the middle of the height, with a slight inward 

 curve gradually becoming broader. Each of these ribs then branches into three or 

 four, which are very regular equidistant and rounded, and pass over the siphonal 

 side, where they attain their maximum development. 



Sutural line very indistinctly seen. 



Locality and stratigraphical position. — Mazar Drik ; Folyphemm-\im.Q^\,onQ. 



'Remarks. — The chief distinguishing characters of this species are the moderate- 

 ly strong ribs extending over the whole of the sides from the umbilical edge to the 

 siphonal side, and the comparatively narrow umbilicus. The specimen from Ba- 

 luchistan, although considerably deformed by pressure, shows the above-mentioned 

 features so exceedingly well, that there can be no doubt as to its identify with 

 the form from Kutch. 



Professor Waagen's figures are in this case entirely misleading, figs. 2a and 25 

 being found to differ materially from the original. They lead one to believe 

 that the original is an exceedingly well preserved specimen ; this is, however, 

 by no means the case, it being considerably damaged. If we take first fig. 

 2a we notice that (1) the sharp, well-defined umbilicus, as depicted, does not exist in 

 the original, it being almost entirely filled up with matrix, so much so that there is no 

 sharp outline, particularly on the left-hand side ; (2) the upper third of the figure is 

 entirely restored, this portion of the original being weathered to such an extent 

 that the first four ribs of the figure do not in reality exist ; (3) at the lower left-hand 



