OF TUBULAR AND CELLULAR POLYPI, AND OP ASCIDIiE. 387 



h. Another, of which the polypus, with a deformed shell, is recently completed. 

 X 200. The ends of two of its arms, more enlarged, 

 c. A sprout in the act of growth. 

 c 2. The same sprout six hours later. The arrows show the course of the cur- 

 rents within. 

 c 3. The same after six hours more : rudiments of a shell forming, 

 c 4. Further growth of the same in eight hours. The diverging lines at the 

 end of c, c 2, c 3, &c. accompany the forming process, 

 c 5 to 9. Progress of the imperfect cell and polypus towards completion. 

 « 2 to 5. Stages in the absorption of the polypus a. 



Plate X. 



Fig. 1. Campanularia dichotoma} with ovaries in different states (page 375.). 



a. An immature one, of which the shell appears to be in progress of growth at 



the end. b. One more advanced, 



c. Another, which has begun to protrude its ova. 

 b2, b'S. Exclusion of the first ovum from the ovary b, 



b 4. The young polypus discharging its active particles. 



b5. Its appearance after their discharge, before the emergence of the second 



ovum. 

 b 6. The same ovary after the first and second young polypus had been absorbed, 

 when the third was become rugose, and the fourth had just discharged its 

 particles. 

 c2. The ovary c with the columella remaining, before discharging its last ovum. 

 Fig. 2. The simple Campanularia described page 376. 

 Fig. 3. Coryne (page 376.). 



a. Its small cell, in the axis of which the alternate current was seen. 



b. The naked ova, in the peduncles of which the same current appeared. 



Plate XI. 

 Animals of the Ascidia described page 378. The interior is seen through the 



transparent coats. 

 Fig. 1. Manner of their growth. 



Fig. 2. The right side of one supported on its peduncle. 

 Fig. 3. The left side of another. 

 Fig. 4. The back. 

 Fig. 5. The front and base. 

 Fig. 6. A sprout ending in the rudiment of an animal. 



The letters refer to the same parts in all. The small arrows denote the 

 course of the circulation when the forward impulse is given by the heart; 

 the large arrows at the orifices, the influx and efflux of water. 

 a. TJie envelope. b. The mantle. 



