HALECIUM FILICULA. 15 



Lafoeina and Oplorhiza afford the only known instances in which organs 

 resembling true nematophores occur outside of the family of the Plumularidae. 



Oplorhiza parvula. 

 PI. VII. Figs. 1-3. 



Trophosome. — Hydrosoma very minute, scarcely attaining a line in height. 

 Hydrothecge deep, narrowing towards the summit and towards the base ; 

 peduncles with about two rings just below the hydrotheca, and several less 

 distinct ones at their origin from the hydrorhiza. Hydrorhizal appendages 

 very minute, clavate, scattered over the upper side of the hydrorhiza. 



Gonosome not known. 



Dredged south of Marquesas from a depth of 296 fathoms. 



Family HALEOID^. 



Genus HALECIUM Oken. 



Halecium filicula. 



PI XL Figs. 1-4. 



Trophosome. — Hydrocaulus attaining a height of about three inches, alter- 

 nately branched; branches pinnately disposed; internodes rather long; main 

 stem and principal branches fascicled, but becoming monosiphonic toward 

 their distal ends. Hydrophores* with one or more usually oblique and 

 irregular annulations at their base, then gradually widening from the most 

 distal annulation to the summit, where they terminate in a circular and 

 abruptly everted margin. 



Goiwsome not known. 



Dredged south of Marquesas from a depth of 140 fathoms. 



This species is rendered striking by the graceful trumpet-shaped form of 

 its hydrophores. Many of these are provided with a double or even triple 

 margin, caused by the hydranth in its growth leaving behind it the old 

 dilated extremity of the hydrophore, and becoming encircled by a new one, 

 — a common occurrence among the various species of Halecium. 



* The genus Halecium is destitute of true hydrothecje, and the term hydrophore is here used for 

 the appendages of the stem which take the place of the hydrothecse in giving support to the hydranths. 



