HYDROIDA II 



antarctica Jaderholm must doubtless be removed to a genus of their own, more closely related to 

 Kirchenpaueria. It would thus not be advisable to introduce a new diagnosis for Schisotricha; the 

 genus should rather be allowed to disappear definitely as synonymous with Polyplumaria, which latter 

 generic appellation is older, and originally better defined. For Plumuiaria gracillima G. O. Sars there- 

 fore, it will be best to take an entirely new generic name. 



Polynemertesia gracillima (G. O. Sars). 



1873 Plumuiaria gracillima, G. O. Sars, Bidrag til Kundskaben om Dyrelivet paa vore Havbanker, p. 86. 



1893 Plumuiaria groenlandica, L,evinsen, Meduser, Ctenophorer og Hydroider, p. 63, tab. VIII, figs. 10 12. 



Single pinnate colonies with 

 monosiphonic or in the basal parts 

 polysiphonic main stem. The mono- 

 siphonic stem is divided by trans- 

 verse nodes into iuternodia, which 

 bear distally a short apophyse, di- 

 rected obliquely forward, turning 

 alternately to either side of the me- 

 dian line. The stem has no hydro- 

 thecse, but bears mobile sarcothecee, 

 two unpaired, somewhat asymme- 

 trically arranged on the basal part 

 of each internodium. The apophyse 

 has a "mamelon" on its upper side 

 near the stem; beside this on the 



rear side a mobile sarcotheca, and 

 o c 



Fig. XXXIV. Polynemertesia gracillima from the Davis Strait als an Unpaired mobile Sarcotheca 



>| [type specimen of Plumuiaria groenlandicd\. a. Internodium of the distallv ill the median line The 

 ' I stem with primary apophyse. b. Second internode of a prim- 



ary hydrocladium with secondary apophyse, showing a distinct apophyse bears a Secondarily bran- 



"mamelon". c. Hydrothecate internode. (X 80). 



hydrodadium; the hydroc l a . 



dium is divided by transverse nodes into irregular internodia, of which every alternate one bears two 

 unpaired sarcothecse in the median line, every other a median hydrotheca, a supracalycine pair of sar- 

 cothecse at the opening of the same, and an unpaired proximal, and as a rule an unpaired distal sarco- 

 theca in the median line; on the distal parts of the hydrocladia the hydrothecaless internodium often 

 melts into the hydrotheca-bearing internodium. The basal internodium of the hydrocladium is hydro- 

 theca-bearing; the following small internodium is furnished at the middle with an apophyse directed 

 obliquely forward and bearing the secondary hydrocladium; from the second segment of the latter there 

 proceeds as a rule a further hydrocladium in the same manner; these secondary (tertiary) apophyses 

 also are provided with a "mamelon" and two mobile sarcothecse, as in the case of the primary apo- 

 physe. The secondary hydrocladia are of the same structure as the primary. The hydrothecse are 

 small, with slightly outward curving opening margin, and are throughout their entire length fused 

 with the internodium. 



