388 MR. LISTER ON TUBULAR AND CELLULAR POLYPI, AND ASCIDI^. 



c. The branchial sac, with its four rows of spiracles. 



d d d. Its line of junction with the mantle above and behind. 



d. Vertical dorsal stripe, (fig. 4.) 



e, e. Finger-like processes projecting from the branchial sac into the cavity of 

 the mouth within, (fig. 2, 4.) 



f. Cavity between the sac and mantle, ending in the funnel/'. 

 /". Ligaments stretched between the sac and mantle, (fig. 4, 5.) 



g. The oral opening. g". Its tentacula. (fig. 2, 4.) 



h. The downward stream of food which flows into the oesophagus h'. (fig. 2, 5.) 

 iki2. The stomach, its fore part enveloped by the liver? (fig. 2, 5.) 



k. The vent terminating the intestinal canal. 



/. Lacteals ? uniting near a mass of transparent globular bodies, with which two 

 lobes are connected, (fig. 2.) The latter are wanting in some individuals. 



m. The heart. 



n. Point where the back stream of blood communicates with the heart when 

 the peduncle is severed, (fig. 2.) 

 Fig. 7. A portion of the branchial sac, more magnified, to show the cilise surround- 

 ing the spiracles and the particles of the blood. 



Plate XII. 



Fig. 1. Polyclinum (page 382.), with a portion of the same more magnified. The 

 branchial sacs, &c. are seen through the transparent common coat. The 

 arrows pointing inwards indicate the oral openings ; those pointing out- 

 wards, the common funnels. 

 a, a. Ledges on the interior of the branchial sac, each ending at a moveable 

 spiral process in front, seen in two of the animals. 

 h. The heart of one of them. 



c. Vent of the same, with other viscera imperfectly seen. 



d. Appearance of a spiracle when the cilise are closed. 



Fig. 2. Flustra pilosa, encrusting a fucus, and single animals of the same, seen 

 through the shell and coat (page 384.). a. The shell. 



b. Valve in the coat, through which the ciliated arms c, and the mouth are pro- 

 truded, b'. The short sheath. 

 c 2. The arms when drawn in, with the neck d folded back. 



e. Pouch (containing the stomach, liver, &c. ?). 



/. Place of gyration of particles in the intestine. g. Rectum. 



h. Ligaments or muscles between the animal and the base of the cell. 

 Fig. 3. Flustra papyracea (page 384.). The animals folded in their cells. The letters 



in this and the following figures refer to the same parts as in the last. 

 Fig. 4. Anguinaria angulna (page 385.). 

 Fig. 5. Tibiana (page 385.). 

 Fig. 6. A zoophyte described page 385. 



