12 Messrs. R. B. Newton and G. C. Click on some 



to have had its greatest thickness at the margin of the 

 umbilicus. This seems to have been relatively small and may 

 possibly have been closed, but unfortunately it is obscured 

 in both specimens. The sides are flattened and convergent 

 and their outer half is slightly concave ; the periphery is 

 flattened, is about one-half the width of the sides, where the 

 shell has a diameter of about 90 mm., and has subangular 

 margins, and in one specimen there is a shallow longitudinal 

 groove almost close to the margin. The whole surface is 

 ornamented with rather coarse lines of growth, which in 

 crossing the whorl pass from the umbilical margin across the 

 lateral area in a slightly backward direction, and with a 

 feeble orad-concave curve at about the middle of this area as 

 far as the subangular peripheral margin, where they turn 

 rather abruptly backward, so as to form a relatively deep 

 hyponomic sinus on the periphery. The position of the 

 siphuncle is not seen, and the septa are not shown. 



In its crushed condition, showing only the ornaments of 

 the test, and neither the position of the siphuncle nor the 

 form of the suture, its identification is rendered extremely 

 difficult. 



The Arabian fossil bears much resemblance to Nautilus 

 hexagonus, described by J. de C. Sowerby * from the Calca- 

 reous grit of Shotover, Oxfordshire, and of Abingdon, Berk- 

 shire t., &c., the ornaments of the test corresponding exactly 

 with those shown in Sowerby's figure; but the Arabian 

 species appears to have had relatively a narrower periphery. 

 The specimen from near Charee, in Cutch, that J. de C. 

 JSowerby J referred with a query to that species because it 

 differed " in having a smaller umbilicus and in being more 

 rounded/' is referred to JSautilus calloviensis, Oppel§, by 

 Waagen ||, who states that in Cutch it is found in beds asso- 

 ciated with Macrocephalites macrocephalus. From the Upper 

 Jurassic rocks of Mombasa in East Africa Beyrich ^[ records 

 a fragmentary specimen as being allied to Nautilus hexagonus. 



* J. de C. Sowerby, Min. Conch. toI. vi. p. 55 (1826), pi. dxxix. fig. 2. 



t The species has also been recorded in rocks ranging from the Stones- 

 field Slate (Great Oolite, Bathonian) up to the Kiineridge Clay (see A. H. 

 Foord, Cat. Foss. Ceph. Brit. Mus. pt. 2, 1891, pp. 235-236), but it is 

 very doubtful if all these records refer to Sowerby's species. 



X J. de C. Sowerby, Trans. Geol. Soc. [2] vol. v. pt. 2, 1840, p. 329, 

 pi. xxiii. fig. 4, expl. of plate (unpaged). This specimen is now in the 

 Museum of the Geological Society of London. 



§ A. Oppel, ' Die Juraformation,' 1856-8, p. 547 (1857). 



|] W. Waagen, 'Jurassic Fauna of Kutch ' (Pal. Indica), vol. i. Cepha- 

 lopoda, pt. 1, 1873, p. 18. pi. iii. figs. 2 a,b. 



5[ H. E. Beyrich, " Ueber Hildebraudt's geologische Sammlungeu von 

 Mombassa," Monatsber. d. k. Preussischen Akad. d. Wissenschaften za 

 Berlin, 1878, pp. 767-775. 



