THE SPINOUS CELLS. 145 



of the branch. From the higher and outer side of 

 the rim spring five long and slender spines gracefully 

 curved, which are each affixed by a joint to a tubercle 

 on the rim. A sixth spine exactly similar springs 

 from a little below the margin on the outer side,* and 

 a seventh from the middle of the inner rim. In my 

 specimens these spines are of great length ; on some 

 of the older cells I have seen them four and even five 

 times as long as the cells. The spines grow after the 

 cells are formed ; for on the same branch may be seen 

 oval cells not yet opened, yet containing the polype, 

 without the least appearance of spines ; others on 

 which they are just budding ; others on which they 

 are short but distinct ; and so on in all intermediate 

 stages of growth, through those in which they are - 

 perfect in length and number, to those near the base 

 of the branch, from which the polypes have died out, 

 and from whose margin the spines have been either 

 partially or wholly broken off. The polypes that 

 inhabit these cells have about twelve tentacles, 

 but I have not been able to see one in a state ol 

 expansion, beneath the microscope. They remain 

 contracted within their cells, their tentacles wrinkled 

 up and pressed together, and showing no voluntary 

 motion, except now and then a spasmodic contraction, 

 on a slight shifting of some of their parts. Their 



* Dr. Johnston (Br. Zooph. i. 335,) says, "on the inner side," but 

 I am sure this is a mistake. The perfect transparency of these crea- 

 tures often renders it difficult to determine on which side of the glassy 

 surface any given point is. By delicate focusing, however, I have dis- 

 tinctly proved this spine to originate on the outside, as indeed was, 

 a priori, more likely. 



O 



