HJALMAR BROCH. 



[REP. OF THE "MICHAEL SARS" NORTH 



Catharina-group are only separated by Nutting 1 ) in regard 

 to growth and branching. Nutting calls attention to the 

 fact that three species of the group, viz. Plumalaria catha- 

 rina, Pluniularia geminata Allman and Plumalaria clarkei 

 Nutting, are closely related, and "may eventually be com- 

 bined in a single species." No doubt, a fourth species 

 of the group: Plumalaria alternata Nutting, may also 

 be included in Plumalaria catharina, the variations in 

 which are no greater than in most other species of the 

 Plumulariidae. 



Antenella Allman. 



Antenella secundaria (Gmelin) Stechow. 



Near Gibraltar (Stat. 20) a few sterile 

 colonies growing on Diphasia pinaster 

 from 141 metres. Near Cape Bojador 

 (Stat. 37) in large quantities with gonan- 

 gia from 39 metres. 



Hincks, 2 ) who considered this spe- 

 cies to be a variety of Plumalaria catha- 

 rina Johnston, reports that its gonangia 

 agree with those of the latter species, 

 and BiLLARb 3 ) mentions the gonangia 

 as corresponding to the descriptions 

 given by Hincks; but as yet, no illustra- 

 tion has been given of Antenella secundaria. A female 

 gonangium from Stat. 37 is shown in outline in fig. 2. 



Nemertesia Lamouroux. 



In my paper on Adriatic hydroids 4 ) I pointed out 

 that a large sessile sarcotheca was found on the hydro- 

 cladial base in the corner between the branchlet and the 

 stem. The same thing holds good in the representatives 

 of the genus taken during the cruise of the "Michael Sars". 



Nemertesia ramosa (Lamarck) Lamouroux. 



Near Gibraltar (Stat. 20) some fragments of a sterile 

 colony from 141 metres. Near Cape Bojador (Stat. 37) 

 large quantities, with gonangia, from 39 metres. 



The well-developed sessile sarcotheca of the hydro- 

 cladial base is seen plainly in fig. 3 (s). 



Nemertesia ramosa exhibits great variations. Generally 

 the colonies have several series of hydrocladia. Almost 

 without an exception, the outer parts of the main branches 

 are biserial in the colonies from Stat. 37, and in these 



Fig. 2. Gonangium 

 of Antenella secun- 

 daria from Stat. 37. 

 (X 40). 



Fig. 3. Hydrocladial 



base of Nemertesia 



ramosa from Stat. 



37. (X 40). 



parts the hydrocladia are inserted alternately; fragments 

 of such colonies closely resemble colonies of Plumularia. 

 The fragments from Stat. 20 demonstrate another and 

 rather different phase of variation. Here 

 the hydrocladia near the top of the main 

 branches are placed in opposite pairs; 

 as they are arranged spirally and at 

 right angles to the preceding and fol- 

 lowing pairs, these parts of the colonies 

 are provided with four series of hydro- 

 cladia. Farther down, the branch be- 

 comes 6-serial, three hydrocladia in a 

 whorl, the whorls forming six series of 

 hydrocladia. 



Although the arrangement of the 

 hydroclades is subject to striking varia- 

 tions, the arrangement of the hydrothecae 

 as well as the nematothecae on the hydrocladia is rather 

 constant. Now and then the distal nematophore of an 

 internode with the distal nematotheca has been detached 

 through a node, and looks like an inserted internode, but 

 such anomalies are rare. 



Nemertesia Hartlaubi (Ritchie). 



Near Cape Bojador (Stat. 37) in 39 metres, enormous 

 quantities with gonangia. 



The stem and main branches are dark brown or almost 

 black, showing only indistinct nodes. Near their upper 

 (distal) ends the internodes carry three or four hydrocladia 

 in a whorl; the hydrocladia are slender and of a whitish 

 colour. The successive whorls form six or eight series 

 of hydrocladia. — The hydrocladia are divided into unequal 

 internodes, each alternate one provided with a nemato- 

 theca, the others having in the middle a small hydrotheca, 

 at the mouth of which a pair of nematothecae are placed 

 symmetrically, whereas the unpaired nematotheca is situ- 

 ated proximally in the mesial line of the internode. In 

 the corner between the stem and the hydrocladial base 

 we may observe a sessile sarcotheca (fig. 4, 5), though 

 owing to its very delicate and hyaline structure it is almost 

 invisible in unstained colonies. The gonangia of both 

 sexes (fig. 4 b) are ovate with a large oblique aperture at 

 the summit; they are inserted at the base of the hydro- 

 cladia on the main branches. 



This species shows great variation. In some parts 

 of the colony there are three hydrocladia in a whorl, in 

 others four. It is interesting to notice that, throughout 



1 ) American Hydroids. I. The Plumularidae (Smithson. Institution, Special Bulletin). Washington 1900, pp. 60 — 62. 



2 ) A History of the British Hydroid Zoophytes. London 1868, p. 301. 



3 ) Hydroldes (Expeditions scientifiques du "Travailleur" et du "Talisman"). Paris 1906, p. 207. 



4 ) Hydroiduntersuchungen 111, p. 27. 



