HYDRACTINIA ECHINATA. 30 



Family.— HYDRACTINIID^. 



Hydr actinia ec/dnata, Fleming. (Fig. 7). 



1 specimen dry and 1 in liquid. 



specimens This Hydroid is peculiar on 

 2, 3. account of the form of the 



chitinous skeleton, and of the diversity of the 

 members composing the colony. It is found 

 at low or in deep water, encrusting whelk and 

 other univalve shells inhabited by the common 

 Hermit crab. According to Hincks, it is 

 always found under these conditions, but we 

 have found it on one occasion, on the claws of 

 a large Lobster. 



The ordinary alimentary polypite is white 

 or pink, and in form very like the last species, 

 but the tentacles are arranged in a single 

 circle. In the " select " polypites, the 

 tentacles are reduced almost to nil, but the 

 remnants are well provided with dart sacks. 

 The gonophores are collected together on 

 the body, and are generally pink in colour. 

 Besides these members, there are others 

 similar in form, but much longer, and which 

 have the habit of coiling themselves up, but 

 they do not bear gonophores. They are 



