66 HYDROIDA II 



similar manner appear eight-rowed, with four apophyses in the circle. The same octoserial type was 

 met with at the "Ingolf" St. 87, and from St. 92, we have for the first time specimens with six apo- 

 physes in each circle, giving a twelve-rowed colony. The revolution of the segments is thus charact- 

 eristic of grown colonies, and calls to mind the features noted in Nemertesia ramosa (cf. Broch 

 1912 p. 5). 



From St. 98, the "Ingolf brought a young specimen of Nemertesia antennina which is of con- 

 siderable interest (fig. XXX). The colony is still quite biserial, and can only be distinguished from 

 Plumularia by the sessile "mamelon" of the apophyses. As however, the arrangement of the sarco- 

 thecse and hydrothecse entirely agrees with Nemertesia antennina, I have no hesitation in referring 

 the colony to this species, the more so since altogether parallel stages occur in the following species 

 together with later phases of development. 



Nemertesia antennina is a southern form with wide distribution in the boreal region (fig. XXXI). 

 Towards the south, it goes at any rate as far as Madeira, and is common in the Mediterranean; it 

 belongs to the middle and lower parts of the littoral region, but may exceptionally, as shown by the 

 finds from the "Ingolf" St. 92, go deep down into the abyssal. It has not yet been met with in purely 

 arctic waters, unless the one find from the east coast of Iceland should be so described. 



Nemertesia ramosa Lamouroux. 



1816 Nemertesia ramosa, Lamouroux, Histoire des Polypiers coralligenes, p. 164. 



1903 Antennularia. variabilis, Broch, Die von dem norwegischen Fischereidampfer "Michael Sars" 



gesammelten Hydroiden, p. 10, Taf. IV, figs. 22^25. 



Colonies with branched main stems, polysiphonic in their lower parts, canaliculate in the upper. 

 Apophyses form circles about the internodia of the stem, two to four in each circle, and the internodia 

 are revolved, giving twice the number of longitudinal rows. In the lower parts of the colonies, where 

 secondary tubes cover the primary stem, the circular arrangement of the branches is less distinctly 

 marked. The apophyse has on its upper side a strong, narrow, but high sessile sarcotheca ("mamelon") 

 and 3—4 irregularly placed, mobile sarcothecae. The hydrocladia are divided by transverse nodes into 

 internodia, each of which has a median hydrotheca with a supracalycine pair of sarcothecse at the 

 opening, and one proximal and one distal unpaired sarcotheca in the median line; exceptionally, the 

 distal part with its sarcotheca may be divided by a slight joint from the main internodium. The hy- 

 drotheca is entirely fused with the hydrocladium, and is l /(, to r / 3 the length of the internodium. 



The gonothecce are attached to the apophyse by a short, almost rudimentary stalk. They are 

 oval to pear-shaped, with a distally lateral asymmetrical opening. 



Material : 



"Ingolf" St. 55 63°33' N., i5°o2' W.; depth 316 fathoms, 5,9 



- 85 63°2i' N., 25°2i' W., — 170 



"Thor" 6i°i5' N., 9°35' W.; — 872 metres 



Iceland : Vestmano, — 50 fathoms 



The Faroe Islands: 62°i6' N., 6°o6' W.; — no metres 



6o°5 5 ' N, 8° 5 6' W.; - 840 - 



