110 



THE GEOLOGIST. 



equal portions, is placed on one side, and thereby, the 

 saddle is divided into two very unequal parts, {A. regularise 

 tuberculatus, auritus, lautus, ^c.) 



From these grand divisions, we may imagine that there 

 are many others arising from combination, according as 

 all the saddles or lobes are formed of equal, or unequal 

 parts, or when only the first are found in this condition. 

 But these divisions are entirely confined to species, and 

 cannot be applied in a general manner. To render them 

 more easily understood, I attach the following tabular 

 view, taking the lobes formed of unequal parts, as the 

 point of departure. 



Besides these characters of lobes formed of equal, or 



which adds to their complication, and multiplies their com- 

 binations ; it is that of the relative length of the dorsal lobe, 

 compared with the superior lateral one ; thus in certain 

 cases, the dorsal lobe is longest; and 1st. the lobes are 

 equal, {A. sMatisulcatus^ strangularis, Vernieuliensis, Man- 

 telli, Rhotomagensis, Fleuriansianus, Woolgari) ; 2nd. the 

 lobes are unequal, with unequal saddles, [A. varicosus, 

 Delarnei, Bouchardianus, Roissyanus, inflatus) ; with equal 

 saddles, {A, Largilliertianus). 



The dorsal lobe is equal to the superior lateral lobe, 1st. 

 with equal lobes, [A. Juilleti, Duvalianus, quadrisulcatus, 

 Requienianus) ; 2nd. with unequal lobes ; (A) the saddles 

 ■unequal, (A. simosus, pretiosus, Belus, ligatus, regularise 

 Martinii, ^^c.) ; (B) the saddles equal, (y^. crassicostatus, 

 semisulcatus, latidorsatus, mammillaris, ^c.) 



The dorsal lobe is shorter than the superior lateral lobe, 

 1st. with tlie lobes equal, {A, Ophinrus, sumfimbriatus) ; 



Lobes formed of 

 unequal parts. 



Saddles equal. | "^^^ ^. 

 ^Saddles unequal. | ''"^ 



unequal parts, there yet remains another important one. 



