Blight concavity upon each side of the keel in A. Boulbimsis, and also a 

 greater contraction of the umbilical aperture with a slight elevation around 

 the inner border. In Yorkshire it occurs in the Alum shale of the Upper 

 Lias ; at NaUsworth, and at Stinchcombe it has been obtained in the same 

 position, also in the Lower Sands at Nailsworth and the Upper Sands at 

 Frocester Hill. 



Ammonites Jurensis, Zieten, A. gubernator, Simpson, Large fragments 

 are not uncommon at Frocester Hill, some few small specimens have been 

 found with the test preserved ; fragments have also occurred in the lower 

 zone of the Sands at Nailsworth and in the Upper Lias at Whitby, young 

 specimens have the volutions more exposed and the general figure less 

 inflated than the adult forms. 



Ammonites radians, Eeinecke, A. striatulus, Ziet., non Sow., A. lineatus, 

 Ziet. A species which possesses great variability even in specimens procured 

 from the same locality and bed, a dozen or more examples would be 

 required to illustrate fully these variations of form and ornamentation, 

 neither is it easy in some cases to define the limits of the species, this is 

 more especially the case in certain radians-like Ammonites of the Upper 

 and Middle Lias. Quenstedt has figured a variety with the volutions much 

 exposed and inflated and with delicate closely arranged radii ; another with 

 more enveloped volutions and a compressed form with the name of radians 

 compressus, both these varieties are extremely inconstant, however much 

 they may difier in their form and in the prominence and relative 

 proximity of the radii, it seems impracticable to separate the species into 

 well-defined varieties. Hauer, in his work on the Cephalopoda of the 

 Lias of the North-Eastern Alps, gives as synonyms of this species all those 

 of striatulus Sow. ; he also figures for radians an Upper Lias form which 

 assuredly is not radians and ill accords Avith his description. A. radians 

 in all its varieties may be procured at Frocester Hill, and at other localities 

 wherever the upper zone of the Sands is fossiliferous, in the lower zone at 

 Nailsworth, and in the Upper Lias it is comparatively rare. 



Ammonites insignis, Schiibler, occurs under two forms which are so very 

 dissimilar that some doubt may be felt of the propriety of retaining them 

 as one species, the first of these, or type, is much inflated and enveloped, 

 the other is much more flattened with narrow exposed volutions. The 

 typical form also assumes two distinct aspects in its adult state, the one 

 having a compressed the other an inflated back, the latter being the figure 

 of the young shell of both kinds. The flattened variety, A. fabalis, 

 Simpson, forms a kind of connecting link between A. insignis and 

 A. variabilis, its tubercles and ribs are however more conspicuous thim in 

 the latter species, the keel is much more depressed and the back is 

 rounded, in the aged condition of A. variabilis the back is compressed 



