90 INVERTEBRATA. 



Localities. Upware. 



N. Europe. Louvenmont (Gb'ttingen Mus.). 

 8. Europe. Perte du Rhone (Aptien supr.), Switzerland, 

 Bernese Alps, Basses Alps. 



" A characteristic Aptien species," (Pictet and Renevier, Perte 

 du Rhone, p. 21). 



AMMONITES DESHAYESII, Leymerie. 

 (Plate m., fig. 1.) 



Ammonites Deshayesii, Leymerie, 1842, Mem. Soc. Geol. France, 



t. v,, pi. 17, f. 17. 

 consobrinus, d'Orbigny, Terr. Cre't., t. 47. 



fissicostatus, Phillips, Geol. Yorkshire, t. 2, f. 49. 



In the German collections this form is usually included in 

 Ammonites noricus of Schlotheim (the original types of which came 

 from the Elligserbrink Neocomian clays). But taking Roemer's 

 description and figure of that species as our guide (the original 

 diagnosis being too imperfect to serve), it will be generally admitted 

 that the two names, Deshayesii (Leyni.) and noricus (Schl. ? and 

 Roemer) should be retained for their respective types. They are 

 however very nearly allied, and a connecting chain of transition 

 specimens could, I am convinced, without difficulty be arranged. 

 Ammonites Deshayesii has fewer ribs and coarser than A. noricus, 

 and no tubercles are developed along the outer border where the 

 ribs are deflected to pass over the back. Again the ribs in Am. 

 Deshayesii pass regularly over the back, simply flattening out and 

 deflecting forwards, leaving no such pseudo-keel as we find in A. 

 noricus. 



Only a single fragment is known from Upware, belonging to a 

 variety with broad obtuse ribs. 



It is an interesting fact that the more typical coarser-ribbed 

 form of Ammonites Deshayesii, Leymerie, occurs at Upware as a 

 "derived" fossil! 



Localities. Upware ( Woodw. Mus.), Speeton (Upper Neocomian) , 



Atherfield. 



N. Europe. Brunswick. 

 S. Europe. Paris Basin, 1'Aube. 



