AND SPECIES OF IIYBIIOIDA. 2G5 



regular internodes, which, correspond in number to the pairs of 

 hydrothecse. 



Desmoscyphus Buskii. Plate XIV. figs. 3-7. 



Trophosome. Hydrocaulus attaining a height of about 3 iuclies ; 

 main stem sending off at irregular and distant intervals pinnately 

 disposed ramuli, which are much attenuated at their origin, and 

 are divided into regular internodes, each of which carries one pair 

 of hydrothecc'e. Hydrothecse swollen below, narrowing towards 

 the orifice, and here slightly curving outwards ; orifice oval, entire ; 

 pairs of hydrothecse closely approximate on the pinnse, but on the 

 main stem separated from one another by considerable intervals ; 

 main stem with only an occasional joint at distant and irregular 

 intervals. 



Gonosome. Gronangia ovoid, with a truncated contracted sum- 

 mit, springing from the front of the pinnse between the diverging 

 summits of the hydrothecse. 



Locality. New Zealand, Mr. Susie's collection. 



The present Hydroid occurs attached to a Sertularella indis- 

 tinguishable from the widely distributed Sertularella gctyii. The 

 greatest diameter of the hydrothecse is not seen in a directly 

 front or in a directly lateral view of the stem or pinnse, but only 

 when viewed in a position intermediate between these two. The 

 inner surface of the gonangium just within its orifice is set with 

 some irregular short furcate spines. 



Stnthecitjm. 



Trophosome. Hydrocaulus divided into intei'nodes, each inter- 

 node carrying a pair of opposite sessile hydrothecse. 



Gonosome. G-onangia supported upon peduncles which spring 

 from within the cavity of certain hydrothecse, where they take the 

 place of the hydranth. 



The genus Synthecimn is characterized by a feature wbich is 

 absolutely without parallel in any other known group of hydroids. 

 This is found in the relation of certain hydrothecse to the gonaugia, 

 the peduncle of the hydrotheca being enclosed within the cavity 

 of the gonangivim. 



The hydrothecse which thus carry gonangia difler in no respect, 

 either in form or position, from those which continue to exercise 

 the normal function of giving protection to tlie hydranth ; and I 

 can find no clue to the meaning of this most exceptional character . 



