cnaP. IXx.] ZOOPHYTES. 201 
many observations on the lower marine animals,* but they are 
of little general interest. I will mention only one class of facts, 
relating to certain zoophytes in the more highly organized divi- 
sion 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 thee 
lower mandible can be opened much wider than in a real bird’s 
beak. The head itself possesses considerable powers of move- 
ment, 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 evi- 
dently 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 corallires 
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 a 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 fur- 
nished 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 
* J was surprised to find, on counting the eggs of a large white Doris 
(this sea-slug was three and a half inches long), how extraordinarily 
numerous they were. From two to five eggs (each three-thousandths of an 
inch in diameter) were contained in aspherical little case. These were 
arranged two deep in transverse rows forming aribbon. The ribbon ad- 
hered by its edge to the rock in an oval spire. One which I found, mea- 
sured nearly twenty inches in length and halfin breadth. Fy counting how 
many balls were contained in a tenth of an inch in‘the row, 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. Vo fallacy is more common with naturalists, than that the 
numbers of an individual species depend on its powers of propagaticn. 
. 
