158 THE TRANSFORMATIONS OF THE ANIMAL WORLD 



transverse stripes. This branch goes from the 

 lower Lias to the Turonian. 



2. The Phylloceras Partschi series, with the last 

 whorl ornamented with large folds with transverse 

 stripes. This branch extends from the Lias to 

 the Barremian. 



3. The Phylloceras tatricum series, with a shell 

 ornamented with transverse excrescences at in- 

 tervals, but not striped. This extends from the 

 lower Jurassic to the Barremian. 



4. The Phylloceras capitanei series, ornamented 

 with from four to nine constrictions, directed 

 obliquely forward. Extends from the middle Lias 

 to the end of the Jurassic. 



5. The Phylloceras ultramontanum series, orna- 

 mented with constrictions first directed forward, 

 then bent back at right angles and towards the rear. 

 Has besides coarse stripes on the outer half. Extends 

 from the lower Jurassic to the Valanginian. 



These five series follow one another clearly, 

 with a richness of form varying with the epoch and 

 the series ; but they possess a somewhat different 

 vitality. The fourth does not go beyond the 

 Jurassic ; the fifth reaches the Valanginian ; the 

 second and third persist up to the end of the Neo- 

 comian ; and finally, the first alone survives the 

 Jurassic and the lower Cretacean period and ends 

 in the Chalk. 



Most of the genera called bushy, that is to say 

 rich in species, exhibit an evolution by parallel 

 branches similar to that of the Phyllocerata, and 

 merit, like the latter, the name of polyphyletic 

 genera. Very numerous examples may be quoted 



