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V. On a new form o/Corynoid Polypes. By Philip Henry Gosse, Esq., F.B.S., A.L.S. 



Read December 2nd, 1856. 



Although every discovery of a new species of animal ought to be recorded with as 

 much precision as can he commanded, it is not every such dlscoveiy that Is worthy of 

 hemg made the subject of a memoir presented to a learned body; but the form and 

 maimers of a creature wluch has lately fallen under my notice appear so anomalous, 

 that I am induced to bring it under the notice of the Linnean Society. 



In the summer of 1855 I happened to have, in one of my marine aquaria, several 

 specimens of a Sabella, which I believe to have been identical with the Amjihitrite vesi- 

 culosa of Montagu (Linnean Transactions, vol. xi. p. 19). The largest of these had been 

 some time in my possession, and, probably owing to the habitual stUlness of the water 

 in the vessel, not holding in suspension the particles of mud, that ordinarily enter into 

 the composition of the tube, the latest-formed portion was composed of pure transparent 

 chit'me, without any perceptible earthy element. This clear terminal portion of the tube 

 I perceived to be occupied by a curious parasite. About twenty bodies having a most 

 ludicrously-close resemblance to the human figure, and as closely imitating certain 

 human motions, were standmg erect around the mouth of the tube, when the Sabella 

 had retired into the interior ; and were incessantly bowing and tossing about their arms 

 in the most energetic manner. 



As soon as I had a little recovered from my surprise at this strange display, I began to 

 extunine the performers more in detail. A slender creeping thread, irregularly crossing 

 and anastomosing, so as to form a loose network of about three meshes in width, sur- 

 rounded the margin of the Sabella's tube, adhering firmly to its exterior surface, in the 

 chitinous substance of which it seemed imbedded (see PI. XX. fig. a). Here and there 

 free buds were given off, especially from the lower edge ; while from the upper threads 

 sprang the strange forms that attracted my notice. These were fusiform, bodies, about 

 -^'oth of an inch in height, whose lower extremities were of no greater thickness than the 

 tliread from which they sprang, with a head-like lobe at the summit, separated fi-om the 

 body by a constriction, immediately below which two lengthened arms projected in a 

 direction towards the axis of the tube. 



Such was the external form of these animals ; and their movements were still more 

 extraordinary. The head-lobe moved to and fro freely on the neck ; the body swayed from 

 side to side, but still more vigorously backward and forward, frequently bending into an 

 arch in either direction ; while the long arms were widely expanded, tossed wildly upward, 

 and then waved downward, as if to mimic the actions of the most tumultuous human 

 passion. 



Whenever the Sabella protruded from its tube, these guardian forms were pushed out, 

 VOL. XXII. J Q 



