Van Name. — Simple Ascidians. 
PLATE 50. 
Fig. 39. Caesira arenata (Stimpson). Large tentacle from rather large 
individual. X 17. 
Fig. 40. Caesira arenata (Stimpson). Part of right side of branchial sac. 
X 19. 
Figs. 41 and 42. Caesira arenata (Stimpson). Dorsal tubercles of two in- 
dividuals. Fig. 42 shows the usual form. X 19. 
