300 



three (sessile] in a line along the intervening internodes ; 

 many distributed over the main stem and creeping sto- 

 lon ; GONOTHEC^: springing from the base of the hydro- 

 thecse ; (male) elongate-ovate, slender, tapering above 

 and below; (female) pear-shaped, operculated, with a 

 two-jointed stalk, bearing two nematophores near the 

 base. 



THE salient character by which this exquisite species may 

 be distinguished from all its British congeners is the 

 arrangement of the pinnse in exactly opposite pairs. This 

 gives it a very distinctive habit; and it has besides a 

 peculiar delicacy and beauty of its own. The pinnse slant 

 upwards ; they are also set forwards on the stem, and the 

 plumes have therefore the appearance of being partially 

 folded. A little above the point of origin a single joint 

 occurs ; and throughout the rest of the pinna the inter- 

 nodes which bear the calycles alternate with others on 

 which two or three sessile nematophores are ranged in a 

 line. 



The lateral nematophores on the hydrothecae exhibit a 

 curious peculiarity : they are mounted on peduncles, by 

 which they are raised nearly to the level of the rim, and 

 are beautiful objects for examination with the microscope. 

 There is an extraordinary profusion of these curious organs 

 on this species, and they are present on the creeping 

 stolon as well as on almost every other portion of the 

 polypary. 



The cup or bowl that surmounts the nematophores, and 

 contains the thread-cells imbedded in a granular mass, is 

 ample and patulous. I am not acquainted with any 

 zoophyte in which their structure can be studied to more 

 advantage. 



The reproductive capsules bud from the portion of the 

 pinna or stem immediately below the hydrotheca, between 



