MANUAL OF NATURAL HISTORY. 345 



series in the same plane, forming linear 

 branches of a dichotomously divided, phy- 

 toid, erect polyzoary. 



II TRIBE. — Jointless Ascidian-Polyps (Inarticulata). 



Polyzoary continuous throughout. 



4. Family. — Club-celled Ascidian-Polyps (Scrupa- 



riidae). Cells disposed in a single series ; 

 junctions rigid, or of the same consistence as 

 the cells; polyzoary usually loosely adnate. 

 The cells are elongate, clavate, with an 

 oblique, subterminal aperture with a simple 

 margin. 



5. Family. — Alternate-celled Ascidian-Polyps (Far- 



cimenariidse). Cells disposed in a double or 

 multiple series round an imaginary axis, 

 alternate, forming cylindrical branches of 

 an erect, dichotomously divided, continuous 

 polyzoary. 



6. Family. — Opposite-celled Ascidian-Polyps (Ge- 



mellariidse). Cells disposed in a double or 

 multiple series ; cells opposite, in pairs. Dif- 

 fers from Bicellariidce in general habit, in 

 the position of the cells in pairs, and in the 

 absence of avicularia. 



7- Family. — Tentacular Ascidian-Polyps (Cabe- 

 reidse) . Polyzoary dichotomously divided into 

 ligulate, bimultiserial branches ; on the backs 

 of which are vibracula or avicularia, one 

 common to several cells ; avicularia sessile. 



8. Family. — Bicellular Ascidian-Polyps (Bicella- 



Q 5 



