90 



4. HYDR ACTINIA ECHINATA (Fleming). 



Frequently on old univalve shells. Alder. 



Very common on Buccinum undatum, and a dead shell of 

 Natica. 



Gonophores : September and November. 



Many of the specimens obtained were very dense colonies, 

 and the crowded hydranths were growing up the sides and on top 

 of the spines. These colonies also showed the remarkably large 

 swollen hydranths (scattered amongst the normal hydranths) 

 noted by Marktanner in connection with another species of 

 Hydractinia. These zooids measure four times the diameter 

 of normal h3^dranths and twice or three times the height. The 

 entoderm is folded into convoluted ridges, which sometimes 

 gives the zooid a striated appearance externally. 



Family Cladonemid^. 



* CLADONEMA sp. 



A medusoid was described under this title in the report of 1912. 

 Four specimens have since been obtained, and more complete 

 observation of the structure has been possible. It now appears 

 that this is not the j^oung medusoid of Cladonema (as then thought 

 possible) but, considering the presence of four distinct marginal 

 sense-organs (represented in the drawings, but overlooked in 

 comparing it with Cladonema) it seems probable that it is a Lepto- 

 medusa. The number of oral lobes, indistinguishable in the first 

 specimen, is now known to be four. 



The hydroid from which this medusoid originated has not yet 

 been discovered. 



* STAURIDIUM PRODUCTUM, Wright. 



Growing on stones in the Laboratory tanks. 



The four " false tentacles " appear at the same time as the 

 second verticil of capitate tentacles and not with the first verticil, 

 as supposed by Hincks. 



Family TuBULAunD^. 



1. TUBULARIA INDIVISA, Linnaeus. 



Not uncommon at and beyond low water, and in deep water. 

 Alder. 



