112 



THE LIAS AMMONITES. 



cygnipes and Cardinia crassissima ; and he observes that the appearance of this beautiful 

 species has only an instant of duration in time, for in all the Basin of the Rhone it 

 occupies only a very limited vertical space, whilst the remains of Amaltheus margaritatus 

 fills nearly all the enormous thickness of the Middle Lias. 



Table showing the extension of the Middle Lias in the British Islands, Belgium, France, 

 Switzerland, Germany, Austria, and Italy, ivith indications of the Liasian Ammonite- 

 zones found in some typical regions of the European area? 



Ammonite-zones 



of the 



Middle Lias. 



British Islands. 



g 



France, 

 Departments of. 



1 Germany. 

 en 



.5 



CO 



<! 



t-H 



T3 



OS 



To 

 a 



a 



■73 



a 

 a 



a 



bi) 

 u 



a 



S 



o 



K 

 1-5 



a 



cc 



a 



o 



12; 

 * 

 * 

 * 

 * 

 * 

 • . . . 



O 



i 



6 

 sa 

 a 

 o 



>^ 



* 

 * 

 * 



i 



S 



o 



r 



'q3 

 P3 



1 



* 

 * 

 * 

 * 



> 

 o 



c 



a 



CD 





U 

 03 



a 



o 



1-3 



* 

 * 



* 



SPINATUS 



* 

 * 

 * 

 * 

 * 

 * 



* 

 * 

 * 



% 

 % 

 * 



* 

 * 



* 

 * 



* 

 * 

 * 

 * 

 * 

 * 



* 

 * 

 * 

 * 

 * 

 * 



* 

 * 

 * 



* 

 * 

 * 

 * 

 * 



* 



* 



« 



* 

 * 



* 

 * 

 * 

 * 

 * 



* 

 * 



MARGARITATUS 



HENLEYI 



IBEX 



JAMESONI 



ARMATUM 





j 





In the above table I have separated the Armatmn from the Jamesoni zone, although 

 united vi^ith it in the text, because the stratum vi^ith Aegoceras armatum forms a good 

 Ammonite-zone, although most of its other Molluscan Pauna ascend into higher beds. 

 When the Armatum-^ow^ is described and figured it will be shown that a most 

 interesting series of forms range themselves around the original Sowerbyan type, although 

 differing in many specific characters from that Ammonite ; the whole forming a remark- 

 able assemblage of the Aegoceratid^, which appeared with the dawn of the Middle 

 Lias, and had, it would seem, a very limited life in time. 



' In addition to the works already cited in the description of the different zones of the Middle Lias on 

 the European Continent I have to add ' Geologic der Schweiz,' by Professor B. Studer, Zurich, 1851 ; 

 'Die Cephalopoden aus dem Lias der Nordostlichen Alpen," by Franz Ritter von Hauer, Wien, 1856; 

 ' Studii geologici et paleontologici sulla Lombardia,' by Stoppani, Milan, 1857; 'Der Jura in Frankeu, 

 Schwaben, und der Schweiz, verglichen nach seinen palseontologischen Horizonten,' by Dr. \V. AVaagen, 

 Munich, 1864. 



