260 " ENDEAVOUR " SCIENTIFIC RESULTS. 



species of Sertularella and Thuiaria. Thecocladium is another 

 genus founded on the regular occurrence of a feature not at 

 all uncommon in other forms. Hypopyxis, as 1 have pointed 

 out in Part II, is to be referred to Levinsen's genus Thuiaria, 

 unless, which is doubtful, the pouch-like appendages should 

 prove to be, as Allman supposed, sarcothecse. 



As the most convenient course, in the present unsettled 

 state of the classification, the family is here taken to include 

 the genera which it has been customary to assign to it, and 

 the genera themselves are taken for the most part in their 

 old signification. They comprise species of Sertularia, Sertu- 

 larella, Thuiaria, Selaginopsis (Dictyocladium), Hypopyxis , 

 and Synthecium. The last-named genus must, according to 

 Levinsen, be removed to the Lafoeidse, in consequence of the 

 absence of an operculum, but Stechow regards the Synthecidse 

 as a distinct family. Sertularia elongata, and a number of 

 other species in which also the hydrotheca-margin has six or 

 more teeth but no operculum, are excluded by Levin&en from 

 the Sertulariidae, and are unprovided for in Stechow's classifi- 

 cation ; for these species I propose the new genus LEVINSENIA. 

 I follow Billard in placing Dictyocladium dichotomum, Allman,. 

 under Selaginopsis ; according to Levinsen's system it would 

 be referred to Sertularella. Several of the Sertularice would 

 come under Levinsen's genus Odontotheca, which I am 

 disinclined to accept. And I may here remark that even 

 if it be admitted that this genus is sufficiently distinct from 

 Sertularia, the name Odontotheca has no claim to acceptance. 

 The type is S. operculata, and L. Agassiz in 1862 proposed 

 the genus Amphisbetia for this very species ; the latter name 

 therefore has priority, and should be adopted if it is con- 

 sidered desirable to separate S. operculata and its immediate 

 allies from the other Sertularice. 



Genus LEVINSENIA, gen. nov. 



Hydrophyton branched or rarely simple, hydrothecse bi 

 serial, apertures with numerous teeth, operculum absent. 



While it is still doubtful to what extent observers generally 

 will accept the principles of classification enunciated by 

 Levinsen, there is no doubt that the nature of the opercular 

 structures must henceforth be regarded as of the first 

 importance. 



Regarding two of the species for which the genus Levinsenia 

 is proposed Levinsen remarks as follows : *" An opercular 

 apparatus has not hitherto been found in Sert. elongata and 



1. Levinsen Vidensk. Medd. fra den naturh. Foren, 64, 1913. p. 265. 



