8 REV. THOMAS HINCKS. 



I do not propose to enter at all into this branch of the 

 subject in the present note, but merely to direct attention to 

 a physiological fact, which naturally leads us to infer the ex- 

 istence of some such colonial nervous system as Miiller has 

 described, and of which indeed some such system seems to 

 offer the only explanation. I refer to the simultaneous 

 mocements of the vibracula, which have been noticed in one 

 of the Cheilostomatous genera, and which probably occur in 

 others. This remarkable fact has hitherto attracted very 

 little attention. About four years ago I had the opportunity, 

 in Guernsey, of studying the Caherea Boryi, Audouin, in 

 the living state, and was much surprised to find that the 

 highly-developed vibracular appendages with which it is 

 furnished, instead of acting independently, as these organs 

 do in other Polyzoa, moved together loitli. jierfcct rer/ularity. 

 I was under the impression at the time that the observation 

 was as new as it was undoubtedly interesting ; but I have 

 since ascertained that the fact had not escaped Mr. Darwin's 

 notice, but is mentioned briefly and quite incidentally in his 

 work on the ' Origin of Species.' In that great storehouse of 

 fact and observation it seems to have lain perdu, and I have 

 never met with a reference to it in any Avriter on the Polyzoa. 



Mr. Darwin has not given any detailed description of the 

 species on which his observation was made ; but it is evident 

 from his brief notice of it that it was a Caherea, and it may 

 very probably have been the C. Boryi, which is a cosmopolitan 

 form. 



' In the genus Caherea the Vihraculaaxe enormously developed, 

 and give a very distinctive appearance to the zoarium. In C. 

 Boryi they are long and slender and serrated along one side, 

 while the grooves into which they fall when at rest stretch 

 completely across the posterior surface of the cells. After a 

 short interval of quietude all the vibracula on a shoot are seen, 

 as if moved by one and the sam« impulse, to start into sudden 

 activity, swinging themselves round simultaneously to the 

 front of the cells, and then sweeping backw ards again and 

 resuming their former ])Osition. After another interval the 

 same synchronous and perfectly regular movement takes 

 place, and so on continually. The action is as orderly as 

 that of a machine. 1 Tiiere is something positively startling, 

 after the perfect quiet, in the sudden, simultaneous rush of 

 tlie whole host oi tihracula into energetic activity. 



In this genus then the setiform appendages act not indi- 



' Tills remark is intentled to apply to the movements only and not to the 

 julcrvals between them, whicli vary in length. 



