130 Rev. T. Hincks on Norwegian 



scattered about in the neiglibourliood. From this, at very con- 

 siderable intervals, rise the slender plumose shoots. 



The SertuJaria^ which is of a dwarf and meagre habit, is 

 also distinguished by the largely developed stolon, which 

 creeps unattached over the mud. It is interesting to remark 

 the modification of this portion of the structure in conformity 

 with the nature of the base on which the zoophyte grows. 

 One of the Aglaophenice and two of the Sertularue obtained 

 by Sars from great depths have thus adapted themselves to 

 the peculiar conditions of ooze life. 



Opliiodes 'parasitica^ G. 0. Sars (n. sp.). 



■ Perhaps the most interesting of the many interesting forma 

 for a knowledge of which we are indebted to the energetic 

 researches of the Norwegian naturalist, is the remarkable 

 Hydroid which he has named Opliiodes ]}arasitica. In general 

 appearance and structure it closely resembles a Plumularia^ 

 and might pass on a slight inspection for a stemless variety 

 of one of the smaller kinds. But, instead of the ordinary sar- 

 cothecee characteristic of the Plumularian family, it is furnished 

 with the curious snake-like appendages which distinguish the 

 genus Opliiodes (mihi). Judging from Sars's description and 

 figures, there is no appreciable difference between these organs 

 as they occur in the Norwegian species and on the British 

 OpiModes mirabilis. In each case they consist of a slender 

 and highly extensile tentaculoid body, protected at the base 

 by a small chitinous cup, and terminated at the free extremity 

 by a globose capitulum filled with thread- cells. In 0. para- 

 sitica they are confined to the erect stems, and are not present, 

 as in 0. mirahilis^ on tlie creeping stolon also ; one of them 

 is generally placed a short distance below the calycle ; and 

 sometimes there is another a little above it. But though there 

 is this remarkable point of agreement between the Norwegian 

 Hydroid and the British, they are plainly not referable to the 

 same genus. The affinities of 0. parasitica are with the 

 Plumulariidge ; those of 0. mirabilis are as clearly with the 

 Haleciidffi. Probably the two families are closely related ; 

 in the forms now under consideration they seem to make a 

 near approach to one another. Opliiodes mirabilis differs in 

 some important particulars from the ordinary type oiHalecium ; 

 and the points in which it thus differs approximate it to such 

 a form as the 0. parasitica of Sars. The large polypites, 

 which cannot retract themselves within the calycle, are common 

 to all the Haleciida3 and to the genus Phimularia ; and we 

 now know that organs akin to the sarcothecse are found in both 

 the families. 



