52 NATURAL HISTORY OF OUR SHORES 



by modified pinnae, are very conspicuous, and they are 

 termed Corbulce (" little baskets "). 



So transparent and ethereal are the majority of the 

 Plumularia that to observe them it is necessary at least 

 to place them in a bottle or tube of clear sea-water, and 

 view them against the light. 



Plumularia similis is not an uncommon form. It grows 

 to a height of about two inches, usually on stones, or at the 

 sides of rock pools, often very high up in tide range. 



There is one representative of the family which is not 

 very obviously plumelike, but it is closely related to 

 Aglaophenia. This is Antennularia antennina, so named 

 on account of its resemblance to the antenna or " horns " 

 of a lobster. It grows in erect clumps to a height of about 

 one foot, and may often be seen attached to scallop and 

 oyster shells. In this one the branches are short and bristle- 

 like, arranged around a central axis. 



Some Hydroid zoophytes have polypi so small that they 

 cannot be seen by the naked eye ; others, such as Tubu- 

 laria, one of the Gymnoblastic ones, have polypi nearly as 

 large as a daisy. Some form branches in the shape of a 

 bottle-brush, others are like fans arranged corkscrew-like 

 around an upright stem. 



One species of Sertularia forms hairlike clumps as large 

 as a football, but all come under the characters above 

 described. 



Linking, as it were, these fixed Hydroid zoophytes with 

 the true jelly-fishes the large familiar forms which have 

 no true branched stock alternate generation we have an 

 interesting form in Lucernaria. Two of these are shown, 

 natural size, in Fig. 20, and one is shown enlarged for details 

 of structure. 



. The representative of the Lucernarians found on this 

 coast is termed Halidystus octoradiatus. Its actual position 

 in classification is somewhat debated, but it forms, as I have 



