AMMONITES — ZOOLOGICAL, ETC= 



109 



those lobes, which, with the exception of the dorsal lobe, 

 (which is always so,) are formed at their extremity, by two 

 equal branches separated at the lower part, on the mesial 

 line, by a small accessory saddle, {Am : Duvalianus, Vernieu- 

 lianus, Mantelliij Rhotomagensis, Juilleti, guadrisulcatus, 

 striatisulcatus, ^c. ^c.J 



Lobes divided into unequal parts. — These lobes, instead 

 of being divided into two equal parts, by an accessory 

 saddle at their extremity, are, on the contrary, formed by 

 a single conical branch, which terminates in a point; if 

 there are auxiliary saddles, they are lateral and equal, fA. 

 denarius, Cryptoceras, Leopoldinus, auritus, Mayorianus, 

 varians, Leivesiensis, ^cj. 



Saddles divided into equal parts. — The same divisions, as 

 in the lobes, form the saddles divided into equal parts. 

 They have, at their superior extremity, two equal parts 

 separated by an auxiliary lobe ; they belong in the first 

 instance to all the species having the lobes equal, {A. Duva- 

 lianus, Mantellii, Rhotomagensis, Juilleti, quadrisulcatus, 

 striatisulcatus ;) and to a great number of species having 

 the lobes unequal, {A. denarius, lautus, Dupinianus, Leopoldi- 

 nus, Diphyllus, Velledae, Lewesiensis, Mayorianus, varians, 

 ^c.) ; thus, on the one hand, all the species having the 

 lobes of equal parts, have invariably the saddles formed 

 of equal parts, whilst the greater number also having the 

 lobes formed of unequal parts, have also the saddles formed 

 of equal parts. In eighty-one species having the lobes of 

 unequal parts, sixty-two are provided with saddles having 

 the parts equal, and nineteen only unequal. 



Saddles divided into unequal parts. — The saddles I have 

 thus named, are those which, instead of being divided in 

 the middle by a single auxiliary lobe, are divided by two, 

 so as to have a median foliation, {A. Deshayesi, verrucosus, 

 Martinii, 2oretiosus, Leannotti, impressus) ; or otherwise 

 the auxiliary lobe, instead of dividing the saddle into two 



