CRICK : SPECIES OF NATJTILTIS FROM THE INFERIOE OOLITE. 



125 



Dimeyisions. 



Diameter ... ... ... ... ... ... 148 mm. 



Height of outer whoii ... ... ... ... 88 ,, 



Height of outer whorl above preceding whorl ... 64 ,, 

 Thickness ... ... ... ... ... 73 ,, 



Width of umbilicus 13-5 ,, 



RemarJcs. — There seems to be in the Inferior Oolite more than one 

 concentrically striated Nautilus with strongly sinuate septa, and it is 

 by no means easy to determine which of these is Sowerby's species, 

 for that author gives only a short description and a single figure 



Fig. VI. — Nautilus suhswnatus, n.ssp. a, lateral view, showing the ornaments on the 

 periphery and the course of the suture-line ; b, peripheral view of the same. 

 Inferior Oolite : near Sherborne, Dorset. Drawn from a specimen in the 

 British Museum Collection [C. 4495]. Rather less than one-half natural size. 



of the type. Unfortunately the location of the type-specimen is 

 not known to the writer. Sowerby's description is as follows : — 

 " Sp. Char. — Thick, umbilicate, concentrically striated ; side depressed, 

 conical ; front convex ; aperture obtusely sagittate, truncated ; the 

 septa have a large sinus on each side." He also remarks that "the 

 striae are nearly close together, moderately fine, and elevated ; they 

 gradually disappear towards the mouth"; and that "the greatest 

 diameter is equal to twice the thickness." Two forms of Nautilus 

 from the Inferior Oolite, resembling Sowerby's N. sinuatus, have come 

 u.nder the writer's observation; in one the thickness is a little less, 

 and in the other a little more, than one-half of the diameter. The 

 inore compressed form is, however, also the more finely striated, and 



