26 HYDEACTINIIDJ3. 



If we direct our attention to the alimentary polypites, 

 we find that the proboscis is capable of extraordinary dis- 

 tention, and assumes the most protean forms. In its 

 most marked deviation from the normal condition, it pre- 

 sents the appearance of a wide saucer-like disk, the 

 tentacles standing out round the rim. In the prolific 

 polypite the buccal prominence is small and broadly coni- 

 cal, and is often concealed by the clustering masses of 

 thread-cells. I am inclined to think that the mouth is 

 not absolutely suppressed. Dr. Wright speaks of a 

 whitish spot on the tip of the proboscis, through which 

 he has succeeded in forcing " the contents of the intes- 

 tine ; " and Agassiz describes a mouth in his H. polychna, 

 a species which I am unable to distinguish from our own 

 H. echinata. 



The sporosacs are distributed over the upper part of 

 the body, and attain an immense size as their contents are 

 matured. They are present in all stages of development 

 on the same polypite, one or two being generally much in 

 advance of the rest. The shape and colour vary in the 

 two sexes, the male sporosac being often much elongated 

 and of a vellowish tint, the female roundish and rose- 



* 



coloured. 



H. echinata is liable to be infested by the larvae of a 

 Pycnogon, which manage in some way or other to take 

 possession of the polypites and convert them into nests, in 

 which they pass through certain stages of their develop- 

 ment*. These converted polypites are nothing more 

 than capacious sacs, without tentacles, in which, as in a 

 comfortable nursery, the brood of young Pycnogons spend 

 their early days, feeding 110 doubt on the nutrient juices 

 of the zoophyte. 



* Vide a paper by Dr. Strethill Wright, Jouru. of Microscop. Science 

 (N. S.) vol. in. 



