MR. HUXLEY ON DOLIOLUM AND APPENDICULARIA. 
605 
k. Intestine. 
/. Anus. 
m. Axis of the caudal appendage. 
n. A long membrane of appendage. 
0. Bundles of striated muscular fibrils. 
j). Testis. 
7?'. Efferent duct of testis. 
q. Supposed ovary. 
r. Heart. 
s. Liver. 
t. Muscular bands. 
u. Ciliated sac. 
B. The body of Appendicularia. 
A. The caudal appendage. 
X. Hypopharyngeal band. 
y. Branchial bars. 
z. The system of tubules embracing 
the intestine. 
PLATE XIX. 
The diagrams represent imaginary sections of the principal types of the Ascidian 
family. Without pretending to be strictly accurate, they are sufficiently so to give 
a just idea of the gradations in structure among the different genera, and of the 
essential unity of structure which runs through the group. 
4 I 
MDCCCLI. 
