CHAP, ix.] ZOOPHYTES. 191 



little general interest. I will mention only one class of facts, 

 relating to certain zoophytes in the more highly organized division 

 of that class. Several genera (Flustra, Eschara, Cellaria, Crisia, 

 and others) agree in having singular moveable organs (like those 

 of Flustra avicularia, found in the European seas) attached to 

 their cells. The organ, in the greater number of cases, very 

 closely resembles the head of a vulture ; but the lower mandible 

 can be opened much wider than in a real bird's beak. The head 

 itself possesses considerable powers of movement, by means of a 

 short neck. In one zoophyte the head itself was fixed, but the 

 lower jaw free : in another it was replaced by a triangular hood, 

 with a beautifully-fitted trap-door, which evidently answered to 

 the lower mandible. In the greater number of species, each cell 

 was provided with one head, but in others each cell had two. 



The young cells at the end of the branches of these corallines 

 contain quite immature polypi, yet the vulture-heads attached to 

 them, though small, are in every respect perfect. When the 

 polypus was removed by a needle from any of the cells, these 

 organs did not appear in the least affected. When one of the 

 vulture-like heads was cut off from the cell, the lower mandible 

 retained its power of opening and closing. Perhaps the most 

 singular part of their structure is, that when there were more than 

 two rows of cells on a branch, the central cells were furnished with 

 these appendages, of only one-fourth the size of the outside ones. 

 Their movements varied according to the species ; but in some I 

 never saw the least motion ; while others, with the lower mandible 

 generally wide open, oscillated backwards and forwards at the rate 

 of about five seconds each turn ; others moved rapidly and by starts. 

 When touched with a needle, the beak generally seized the point so 

 firmly, that the whole branch might be shaken. 



These bodies have no relation whatever with the production of 

 the eggs or gemmules, as they are formed before the young polypi 

 appear in the cells at the end of the growing branches ; as they 

 move independently of the polypi, and do not appear to be in any 

 way connected with them ; and as they differ in size on the outer 



and how many rows in an equal length of the ribbon, on the most moderate 

 computation there were six hundred thousand eggs. Yet this Doris was 

 certainly not very common : although I was often searching under the 

 stones, I saw only seven individuals. No fallacy is more common with 

 naturalists, than that the numbers of an individual species depend on its 

 powers of propagation. 



