FAUNA OF THE RHONE BASIN. 105 



Scipionianus indicates that the bucklandian horizon of this basin represents the 

 Lower Bucklandi beds of other basins. 



Dumortier divided his zone of Amm. oxynoius into four beds, distinguished 

 by their faunas. 



The " Davidsoni bed " should have been called Striaries bed, since his Amm. 

 Davidsoni 1 is identical with At/as. striaries. The list of species does not enable 

 one to synchronize these beds with the Tuberculatus beds of Semur or other 

 basins, nor do they show that it is equivalent to any bed above the Upper 

 Bucklandi beds. 



The Stellaris bed' of Dumortier contains, besides the species mentioned in the 

 table, Amm. Locardi, a species of Deroceras, and Amm. Birchi, a form of Microde- 

 roceras ; both of these, therefore, belong to a family distinct from the Arietidse. 

 The presence of Birchi, BoucauUiana, and obtusum show that this, and not the so 

 called Davidsoni bed, is the equivalent of the bed immediately above the Upper 

 Bucklandi beds at Semur. This result confirms our opinion that the David- 

 soni bed of Dumortier should be called the Upper Bucklandi bed. 



Dumortier's Planicosta bed contains Cluniacensis, 2 which is identical with Ast. 

 Collenoti; and this seems to settle the geological position of this important species. 

 Amm. jejumis 3 seems to be an abnormal or diseased Am. miserabile ; Pellati is 

 a young form of Gal. raricostatum ; and armentalisf if one can trust the aspect of 

 the inner umbilical pilae, is a diseased form of Gal. raricostatum. It appears from 

 the figure to be similar to the deformed Amm. longidomus wger of Quenstedt, 5 and 

 other similar pathological forms, in which the keel and channels have been super- 

 seded during growth by pike crossing the abdomen. 



Viticola (Plate XXXI. Fig. 9-13) is the same as the Johnstonian variety of 

 Gal. raricostatum; Edmundi (Plate XXXIX.) is the equivalent of the young of Gal. 

 nodotianum; tardecrescens (Plate XXXI. Fig. 3, 4) may be related to Am.falcaries. 

 The umbilicus, sutures, and general aspect of the last indicate that it is a form 

 of Arnioceras. Oosteri (Plate XXX. Fig. 2-4) is a keeled and channelled form of 

 Arnioceras, with distorted pilae. 



Amm. planicosta, subplanicosla, and Paidi are all varieties of our Der. planicosta, 

 and belong to a family distinct from the Arietidse. 



The three upper beds of Dumortier are apparently the equivalents of the 

 Birchii or Tuberculatus beds in the table of the Cote d'Or basin. 



The notable facts brought out by this table are as follows. There is a 

 regularity in the distribution of the schlotheimian series similar to that in the 

 Cote d'Or basin. Caloceras is not so fully represented in the lower beds, and is 

 equally deficient in the Bucklandi zone. It is represented by a full list of species 

 in the highest beds, with the exception of nodotianum, which is absent. Gal. 

 carusense, however, is more fully represented, and Gal. raricostatum has a greater 

 number of varieties than in any other fauna. The arnioceran series is not so 

 fully represented in the Bucklandi zone, but it is notably richer in forms in the 

 highest beds than in any other fauna. Coroniceras is well represented in the 



1 PI. xxi. fig. 1^. 2 PI. xxv. fig. 8-10. s PI. xxxi. fig. 6-8. 



4 PI. xxix. fig. 1, 2. 6 Die Amm. d. Schwab. Jura, pi. vi. fig. 3. 



14 



