46 



HYDROIDA II 



branches are divided into fairly short internodia, having a hydrotheca on the distal apophyse; the latter 

 is often, though not always, separated from the basal cavity of the hydrotheca by a joint 



The gonothecEe are very large, and proceed from the tubes of the stem and branches, or from 

 the apophyse. They are irregularly oval, flatteued, without spiues or ribs, the females are much larger 

 than the males, often more flattened in proportion, but otherwise of the same shape. 



Material : 



"Ingolf St. 33 67°57' N., 55°3o' W., depth 35 fathoms 0,8° 

 Greenland: Egedcsminde (without further details) 



Store Hellefiskebanke ( ~' — — ) 



Davis Strait, depth 100 fathoms ( — , — — ) 

 _ _ 67°34' N., 55°2o' W., (depth not stated) 

 Iceland: Vadlavig, depth 46 fathoms 

 Vestmano, — 28 — 



Halechivi labrosnvi is an arctic species capable of penetrating into the boreal areas (fig. XIX). 

 In strictly arctic waters it is of very robust build, perhaps the coarsest of all arctic Halecium species, 

 and can hardly be confused with others. In warmer parts, it assumes a somewhat finer structure, but 

 should even here be reckoned among the robust forms. Bathymetrically, the species belongs to the 

 upper part of the littoral region, and has very rarely been observed below this. The few records of 

 its occurrence in the Mediterranean and Atlantic south of the boreal region demand renewed investi- 

 gation, as much would seem to suggest that confusion has taken place. 



Halecium tenellum Hincks. 

 1861 Halecium tcncllitf/i., Hincks, A catalogue of the Zoophytes of South Devon, p. 252, pi. 6, figs. 1—4. 



?i9ii Halecium texfum^ Kramp, Report on the Hydroids the Danmark Expedition, p. 368, pi. 



XXI, figs. 5-6. 



Colonies upright, with mouosiphonic hydrocaulus, and typical, somewhat irregularly sympodial 

 growth. The branches — the new hydrotheca stalks — proceed from close beneath the basis of the 

 terminal prinuir\' hydrotheca, not infrequently in pairs, so that dichotomic ramification takes place; 

 more rarely several branches from the .same point. Pseudohydrocauli are of minor importance in the 

 colonies, the renewal of hydrothecte is not particularly active. The hydrothecse are of medium size, 

 broadening upward from the slight diaphragm and terminating in an often recurvate opening margin. 

 The stalk of the secondary hydrotheca; is ringed, the branches are often ringed throughout their 

 entire length, and exhibit at any rate distinct rings above their origin. 



The gonothecse proceed from the base of the primary hydrothecse, or more rarely, they may 

 be formed as heteromorphotic renovates in the hydrothecaa themselves. The gonotheca is somewhat 

 flattened; viewed from the broad side they are elongated oval, with the distal part cut off transversely 

 or broadly rounded; seen laterally, they are more egg-shaped, with a pointed distal part. They lack 

 hydranth pairs. 



Material: 



"Ingolf St. 87 65°02,3' N., 23°56,2' W., depth no fathoms 



