PLATE XXVII!. 



Class TUNICATA. 



THE SEA-SQUIRT OR ASCIDIAN (Phallusia). 



FIG. 1. ASCIDIAN. x 1. 



i. incurrent or pharyngeal opening : e. excurrent or atrial opening. 



FIG. 2. ASCIDIAN WITH LEFT HALF OF THE TUNIC REMOVED, x 1. 



t. right half of the tunic, attached to m. mantle, at i. pharyngeal 

 and a. atrial openings. 



Note. In this species the intestine and other organs lie on the left side 

 of the animal, while the branchial sac extends over the right 

 side, as seen in Figs. 3 and 4. In these descriptions the pharyn- 

 geal opening is accounted ventral and the atrial opening dorsal. 



FIG. 3. ASCIDIAN WITH RIGHT HALF OF THE TUNIC REMOVED, x 1. 

 5. branchial sac. 



FIG. 4. ASCIDIAN WITH HALF OF THE BRANCHIAL SAC REMOTED. x 1. 



t. tentacles in the pharyngeal opening : e. endostyle : m. mouth : 

 d. dorsal lamina. 



FIG. 5. ASCIDIAN IROM THE RIGHT SIDE : TUNIC REMOVED, x 2. 



s. stomach : g. genital gland : i. intestine : d. genital duct : r. rectum : 

 n. nerve ganglion. 



FIG. 6. TRANSVERSE SECTION THROUGH THE MIDDLE OF THE BODY, x 3. 



t. tunic : m. mantle : 5. branchial sac : I. dorsal lamina : e. endostyle : 

 i. intestine : g. genital gland : r. rectum : d. genital ducts. 



FIG. 7. LARVAL ASCIDIAN. (Fragarium elegans.') x 50. 



