SECTION V. 



THE CLASS OF TUNICATA OR ASCIDIANS. 



THE Tmiicata arc one of the great groups of mollusk- 

 like animals which authors include in the Sub-branch of 

 Molluscoidea. 



They are exceedingly unlike typical mollusks in their 

 general appearance, and very unlike them in many points 

 in their structure. Gegenbaur classes 

 them with the Venues. 



The Tunicates are more or less bottle- 

 shaped or pouch-like, and attached to 

 submarine bodies, are entirely destitute 

 of hard parts, being covered by an elastic 

 tunic, instead of a shell, and some kinds 

 are so transparent as to exhibit plainly 

 their internal structure. 



Some kinds are simple and solitary ; 



' Tumcates . 



others live together in communities ; and A compound cluster of 

 others still are compound clusters (Fig. TuniratPS or ^^ a 



' Bultenia. Reduced. 



6o3. 



Fio. 654. 



FIG. 655. 



Tunicate, Eugyra pilularis, Ver- 

 rill. 



Tunicate, Molgula arena/a, Stimpson. 



