^. HYDROIDA 11 



24 



cogne. Browne's specimens from the Bay of Biscay (1907 p. 25) on the other hand, should not be 

 included here; from the nematothecae, they should be ascribed to Zygophylax, and are plainly identical 

 with the following species. In the northern Atlantic regions, the species appears to follow the warmer 

 water-masses in their progress through the boreal regions; it has exceptionally been found right up 

 in the Barents Sea. 



Gen. Zygophylax Qiielch. 



Upright colonies with sympodial growth. The hydrothecse are narrowly bell-shaped to tubular, 

 not infrequently somewhat asymmetrical in structure, with a low, but strongly developed radially 

 symmetrical diaphragm. The colonies are furnished with small nematothecse. The polyps have a uni- 

 formly developed gastral endoderm. 



Zygophylax biarmata Billard. 



1906 Zygophylax biarmata, Billard, "Travailleur" et ''Talisman", p. 180. 



1907 La/ova pinnata, Browne, Hydroids collected by the "Huxley", p. 25. 



191 1 Lictorclla Leviiiscni, Scemundsson, Bidrag til Kundskaben om de islandske Hydroider II, p. 86. 

 nee 1913 Zygophylax biarmata, vStechow, Hydroidpolypen der Japanischen Ostkiiste, p. 114. 



Colonies upright, in a plane singly or doubly pinnately branched with polysiphonic main stem; 

 the branches nearly regularly alternating. The hydrothecse are alternately placed, turning obliquely 

 forward towards the one side (front) of the colony; i. e. with a tendency to unilateral arrangement. 

 The hydrothecse are mainly tubular, with slightly outward curving margin, narrowing evenly down- 

 wards to a stalk of varying length, which has one or two more or less distinctly marked segmenta- 

 tions. The hydrotheca has a well developed low diaphragm. At the base of the hydrotheca stalk, 

 and occasionally elsewhere on the tubes, there are small, cylindrical nematothec^e, attached to the tube 

 or apophyse by a short and often indistinct stalk, generally in one piece. The apophyse has normally 

 a couple of nematothecse. 



The gonothecse are collected in a primitive, open coppinia (hermaphroditic?) on the stem or 

 main branches; the uematothectc are more richly developed in the gonotheca aggregate than elsewhere, 

 and appear there in large numbers. The gonothecse are flattened ovate, with an outward and down- 

 ward curving neck distalh' on cither side in the transversal plane. 



Material : 



Iceland, near Vestraanno, depth 510 metres. (Type specimen of Lictorclla Lcvinscni). 



The first description of this remarkable species is that given by Billard (1906 p. 180) who 

 had, however, only sterile colonies to go upon. It is undoubtedly the same species which Browne 

 records (1907 p. 25) from the Bay of Biscay, though he ascribes it incorrectly to La/oea piniiata G. O. 

 Sars; the nematothecse show that it must be a Zygophylax^ and the exhaustive description very di- 

 stinctly suggests Zygophylax biarmata. Sa;mundsson (1911 p. 86) describes the species anew under 



