58 



HYDROIDA II 



_ boom. 



Fig. XXVI. The distribution of Plumularia Cathariua in the Northern Atlantic. 

 In the hatched parts the literature notes a common, although scattered occurrence. 



species seems to be somewhat more common than would appear from earlier records; at the two loca- 

 lities noted here, it was present in great numbers. In Greenland waters, Plumularia Catharina has 

 not yet been found. It belongs especially to the upper half of the littoral region. 



Gen. Polyplumaria 1 G. 0. Sars. 



Upright, composite pinnate colonies with polysiphonic branched stem. The apophyses of the 

 stem (the primary tube) bear hydrocladia from which secondary hydrocladia proceed, as a rule from 

 the first hydrotheca-bearing internodium. The apophyse lacks sessile sarcotheca. All the sarcothecae 

 are mobile and two-chambered. 



It is not without hesitation that I retain this genus beside Plumularia, with which it is closely 

 related; it may be a question whether we should here, more than in other cases, base the generic 

 division upon the form of ramification. That I have retained it for the present as a separate genus 

 is due to the fact that its species, from their peculiar appearance, form a well-defined group, sharply 

 distinguished from the remaining ones which have been included in the genus Plumularia. My 

 material is not so extensive as to suffice for a revision of the entire family, a task which becomes 

 more and more imperative as further species continue to appear in the literature. A work such as 



1 Nutting has (1900 p. 83) by a slip of the pen called the genus Polyplumularia. 



