CLASS II.— ORDER H. 



GENERA AND SPECIES. 



JANIA. 



Mossy or hair-like, dichotomous, and articulated ; 

 articulations cylindrical, axe or interior horny ; rind 

 less cretaceous than that of the Corallinas. 



Former zoologists have united the Janias to the 

 genus of Corallinas ; but these two groups of Polypi- 

 doms have characters sufficiently distinct to admit 

 their separation. The Corallinas are constantly 

 trichotomous, whilst the Janias are as regularly di- 

 chotomous ; the former have their articulations more 

 or less compressed, frequently triangular, and only 

 cylindrical in some parts of the Polypidom ; whilst 

 the articulations of the latter are cylindrical from 

 the base to the extremities. The position of the 

 polypi may perhaps be dilQferent : however, every thing 



