330 POLYZOA INFUNDIBULATA. 



the greater number of species, each cell was provided with one head, 

 but in others each had two. 



" The young cells at the end of the branches necessarily contained 

 quite immature polypi, yet the vulture-heads attached to them, 

 though small, were in every respect perfect. When the polypus was 

 removed by a needle from any of the cells, the organs did not appear 

 in the least affected. When one of the latter was cut off from a cell, 

 the lower mandible retained its power of opening and closing. Per- 

 haps the most singular part of their structure is, that when there 

 were more rows of cells than two, both in a Flustra and an Eschara, 

 the central cells were furnished with these appendages, of only one- 

 fourth the size of the lateral ones. Their movements varied accord- 

 ing to the species : in some I never saw the least motion ; while 

 others, with the lower mandible generally wide open, oscillated back- 

 wards and forwards at the rate of about five seconds each turn ; 

 others moved rapidly and by starts. When touched with a needle 

 the beak generally seized the point so firmly, that the whole branch 

 might be shaken. 



" These bodies have no relation whatever with the production of 

 the gemmules. I could not trace any connection between them and 

 the polypus. From their formation being completed before that of 

 the latter ; from the independence of their movements ; from the 

 difference of their size in different parts of the branch ; I have little 

 doubt that in their functions they are related rather to the axis than 

 to any of the polypi. In a similar manner, the fleshy appendage at 

 the extremity of the sea-pen forms part of the zoophyte as a whole, 

 as much as the roots of a tree do of the whole and not of the indivi- 

 dual buds. Without doubt this is a very curious variation in the 

 structure of a zoophyte : for the growing part in most other cases 

 does not manifest the least irritability or power of movement. 



"I will mention one other kind of structure quite as anomalous. 

 A small and elegant Crisia is furnished, at the corner of each cell, 

 with a long and slightly curved bristle, which is fixed at the lower 

 end by a joint. It terminates in the finest point, and has its outer 

 or convex side serrated with delicate teeth or notches. Having 

 placed a small piece of a branch under the microscope, I was exceed- 

 ingly surprised to see it suddenly start from the field of vision by 

 the movement of these bristles, which acted as oars. Irritation 

 generally produced this motion, but not always. When the coral- 

 line was laid flat on that side from which the toothed bristles pro- 

 jected, they were necessarily all pressed together and entangled. 



