CALYCELLA SYRINGA. 207 



the operculinn. The latter is often connected with a 

 curious piece of structure. 



It consists of a membranous tube or sheath, which rises 

 to a greater or less height above the true margin of the 

 calycle, and terminates in a serrated border. Within this 

 sheath, and at the base of the denticulated edge, the oper- 

 culum or lid is placed, composed of several converging 

 segments, Avhich fit closely together and constitute a 

 conical roof to the little dwelling below. The crenated 

 margin of the sheath, which is extremely delicate, rises 

 above the top of it, and forms an ornamental border 

 round it. 



This structure is only met with on some of the calycles, 

 and is so minute and delicate that it requires a high power 

 and careful manipulation to master its details. It is a 

 later growth, and is developed on the older hydrothecse. 

 The lid is sometimes drawn within the calycle and reversed, 

 so as to exhibit the figure of an inverted cone. 



The pedicel of C. syringa is of very various length, but 

 when shortest has three or four rings (or spiral twists). 

 The texture of the calycles is somewhat densely corneous, 

 and they are generally of a deep horn- colour. 



The acrocyst or external marsupium, in which the ova 

 pass through the later stages of their development, is a 

 spherical sac with a gelatinous covering, that rests like a 

 ball on the summit of the capsule *. 



The polypite has about sixteen arms. 



Hab. On other zoophytes and on seaweeds ; very com- 

 mon. 



[Off Reikiavik, Iceland, in 100 fathoms (T. H.).] 



* "Notes on the Reproduction of the Campanulariadse," by the Rev. T. 

 Hincks, Ann. N. H. for August 1852. 



