SYNCOIIYNE EXIMIA. 51 



red bulbs, with a dark reddish-brown ocellus on the 

 outer side, and set with knot-like clusters of thread - 

 cells, the terminal group forming a spherical bulb. 

 Height of the stems 3 or 4 inches in fine examples. 



S. ExmiA has small reddish polypites, with an opake- 

 white proboscis, and a very delicate membranous cup 

 round the base. 



The general colour of the zoophyte is a pale pink. 

 The reproductive buds are mounted on long peduncles, 

 and are developed in large numbers over almost the whole 

 of the body. 



The smoothness of the principal stems and the uni- 

 lateral arrangement of the branchlets are characteristic 

 points. 



S. eximia is one of the Hydroids that are infested by 

 the larvse of the Pycnoyon, a very curious form of Crusta- 

 cean *. The parasitism is of a most extraordinary kind. 

 At a very early stage of their existence the young Pycno- 

 ffons gain access in some way or other to the interior of 

 the Zoophyte, and find their way through the cavity of 

 the coenosarc into the budding polypites, which they oc- 

 cupy, using them as nests during the further stages of 

 their development. 



The growth of the nascent polypites thus invaded is 

 arrested, and they are converted into long clavate sacs, 

 within which the larval intruders find an undisturbed 

 retreat. At the proper time they rupture the investing 

 polypary, and make their exit. 



On a small colony of the Syncoryne I have found as many 

 as five of the Pycnogon sacs. They were of a rose-red 

 colour ; and from one of them the young Crustacean was 

 extricating itself, one or two legs protruding at the top. 



* Vide a paper by Mr. Geo. Hodgo, Ann. X. H. (ser. 3) vol. ix. p. .'fci. 



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