HYDROIDS OF WOODS HOLE. 381 



The genus Lafceina was established by Sars (Bidrag til Kund- 

 skaben om Norges Hydroider) ' for a very minute hydroid found 

 on stems of Perigonimiis, the chief generic character of which 

 was the presence of minute urticating organs, or nematophores, 

 unlike any before known. Levinsen's description is rather inade- 

 quate, and his figures not altogether satisfactory, but to the writer 

 there seems to be so comparatively little in common between his 

 species and that of Sars, that it may be doubtful whether it should 



FIG. 9. i, Axial tubes ; 2, hydrothecae. 



not have been placed under a new genus. Be that as it may, it 

 seems very sure that the present one must find different generic 

 housing. For example, in Sars' genus the hydroid has a reticu- 

 late hydrorhiza, and Levinsen describes something of the sort for 

 L. maxima, but in the present species while there may be com- 

 prised something of the sort, it would be more correct to describe 

 the complex stem as arising from a dense, sponge-like base, etc. 



Concerning the family relations I am not disposed in this 

 connection to enter into any critical review. While the Perisi- 



1 " Saerskilt aftrykt Selsk. Forhandlinger" for 1873. 



