54 



HYDROIDA II 



side. The apophyses have each an unbranched hydrocladium , divided by transverse joints into 

 segments with numerous hydrothecse. Each, or more rarely, every alternate internodium on the 

 hydrocladium has on its distal half a hydrotheca entirely fused down its one side with the inter- 

 nodium, or more rarely having a low free adcauline edge. The hydrotheca-bearing internodia are also 

 distally furnished with a median pore, proximally with a median pore having raised edges, through 

 which the naked sarcostyles pass. The length of the hydrotheca varies between l / 2 and l / s of that 

 of the internodium. 



The gonothecse are situated on the stem or on the basal parts of the hydrocladia, without 



60 



Zoom. _______ 600 . ._._._._._, looo m. ._ tooom. 



Fig. XXIII. The distribution of Kirchenpaueria pinnata in the Northern Atlantic. 

 In the hatched regions a common occurrence is stated by the literature. 



special protective organs. They are oval to pear-shaped, smooth or spiny, often much flattened from 

 the side. 



Forma typica. Short internodia with hydrothecse in length from r /3 to l / 2 the internodium. 



Forma elegantula (G. O. Sars) slender internodia with small hydrothecse, length as a rule from 

 J /5 to '/g of the internodium. 



Material (forma typica): 



Greenland? (without further details). 



The Faroe Islands: (without further details) [= Plumularia echinulata Winther]. 



The synonymy of the species has recently been worked out by Bed ot (1916). It gives us an 

 interesting insight into the variability of a species, and throws a sharp light upon several of the 



