Van Name. — Simple Ascidians 
EXPLANATION OF PLATES. 
PLATE 43. 
Fig. 1. Bostrichobranchus pilularis (Verrill). Tentacles. X 40. 
Fig. 2. Bostrichobranchus pilularis (Verrill). Dorsal tubercle. X 28. 
Fig. 3. Bostrichobranchus pilularis (Verrill). Part of branchial sac of imma- 
ture individual from Station 72. X 43. 
Fig. 4. Bostrichobranchus pilularis (Verrill). Intestinal loop and gonad. 
X20. 
