410 Mr. J. De C. Sowerby on the Genus Crioceratites 



If we arrange the genera of concamerated cephalopods, furnished with a 

 siphon, and with sinuated edges to their septa, according to the straightness 

 or degree of curvature of the shell, we shall have them in the following order, 

 beginning with that which has no curve : 



Baculites. 



Hamites. 



Crioceratites. 



Scaphites. 



Turrilites. 



Ammonites. 



A similar series may be formed of those which have entire edges to the 



septa : 



Beiemnites. 



Orthoceras. 



Phragmoceras. 



i pirula. 



Lituites. 



Nautilus. 



And if we reverse the second of these groups, the genus Goniatites will be 

 found a natural link between them. The genus Crioceratites fills up between 

 Hamites and Scaphites,]\\%i where it was wanted, parallel to Spirula* . 



The gigantic species from the Isle of Wight I shall name, after its for- 

 tunate discoverer, 



^Crioceratites Bowerbankii, PI. XXXIV., fig. 1. 



Spec. Char. — Whorls about four, slightly flattened on their sides, and nearly close ; the inner 

 ones ornamented with numerous radiating furrows, which, gradually disappearing upon the outer 

 whorl, are replaced by eight or ten thick, arched costae, extending completely across the whorl, 

 and largest and most elevated towards the thinly edged, transversely oblong aperture. 



The septa are rather distant, terminating where the costae begin to enlarge. 

 There is generally a short rib almost close to the aperture, and in one speci- 

 men I have noticed an additional short rib between the two long ones which 

 precede the termination. In an individual sixteen inches wide, the septa are 

 one inch and a half apart. 



This fossil occurs in the lower green sand on the south coast of the Isle of 

 Wight. 



* I have seen the drawing of a fossil found in Devonshire by Mr. Austen, of a form similar to 

 tbat of Turrilitesy but with entire edges to the septa ; its situation would be between Lituites and 

 Nautilus. 



