HVDROIDA II 



6? 



6 miles N. by W. of Store Kalso. depth 60 fathoms 



Deep hole at the north point of Nolso, — 100 

 1,5 — 2 miles off the month of Borovig, — 20—30 

 Provences 13 miles in N.75°W., — 30 



Boronses in N.75°\V., — 30 



The Faroe Islands, — 30 



(without further 

 details). 



Nemertesia ramosa is extremely variable as regards arrangement and number of the hydrocladia, 

 as I have previously (1912 p. 5) had occasion to explain. In the revolution of the internodia, however, 

 it follows the same regular principles as Nemertesia antennina. The structure of the stem presents 



Fig. XXXII. Nrmertesia ramosa juv. a. Young colony from "Ingolf" St. 55 



(nat. size), b. hydrocladial internode from the same colony (X So), c. apophyse 

 from the same colony (X 80). d. colony from "Ingolf St. 85 (nat. size', c. apo- 

 b physe from the colony from St. 85 (X 80). 



features of considerable interest. The distal part of its ramifications exhibits the same structure as 

 Nemertesia antennina, having, inside the homogeneous peridermal chitinous^ sheath, coenosarc strings; 

 these parts of the stem are thus canaliculate. Farther down, however, we find secondary tubes closely 

 arranged about the primary stem tube, and the nearer we come to the base, the closer is the network 

 and the thicker the stem. Where these secondary tubes occur, they cover the apophyses more and 

 more, finally burying them altogether, while the hydrocladia here also fall away. Consequently, the 

 basal part of well-developed colonies of Nemertesia ramosa lacks hydrocladia, whereby the colony assumes 

 a highly peculiar appearance. 



At a couple of the "Ingolf" stations, some quite small colonies of Nemertesia ramosa were 

 found; these serve well to show the difficulty of distinguishing the young stages from Plumularia 

 (fig. XXXII). The smallest colony (a) is altogether pinnate; the thin stem is divided into irregular 

 internodia with a varying number of apophyses, but closer investigation shows that the apophyses 

 do not form two regular longitudinal rows, being as a matter of fact alternately somewhat displaced 

 to one side or the other, so that we have here a slight approach to quadriserial arrangement. A some- 

 what larger colony (</), where the stem is slightly thicker, reveals more clearly the displacement of 



9* 



