Ad) ALLMAN, ON’ POLYZOA. 
A remarkable peculiarity, as it would seem, of the fresh- 
water phylactolematous Polyzoa, is the occurrence within the 
perigastric space, at certain seasons, of loose bodies of a 
peculiar nature. For these bodies, formerly confounded with 
ova, Professor Allman proposes the term “ statoblasts.” 
Their form is not exactly the same in the different species, 
but they may generally be described as lenticular bodies, 
varying, according to the species, from an orbicular to an 
elongated oval figure, and inclosed in a horny shell, consist- 
ing of two concavo-convex discs, united by their margins, 
where they are further strengthened by a ring which runs 
round the entire margin, and is of a different structure from 
the disc. In Cristatella and Pectinatella, the statoblast is 
furnished, when mature, with hooked spines. In all species 
the disc is of a deep brown colour, and would seem to be 
composed of a single layer of hexagonal cells. In the 
annulus the cells are larger, and filled with air, so as to sup- 
port the statoblast on or near the surface of the water. 
When placed in circumstances favouring their develop- 
ment, the statoblasts open by the separation of the two faces, 
and there then escapes from them a young Polyzoon, already 
in an advanced stage of development. 
These curious bodies have always been viewed and de- 
scribed as the ova of the Polyzoon, an error formerly partici- 
pated in by the author himself, who is now, however, and 
since the discovery of the true ovary, convinced that they 
are a peculiar form of bud, and must on no account be con- 
founded with genuine ova. 
The statoblasts, moreover, are not developed in the situa- 
tion of the true ovary, which appears in all cases to be situ- 
ated on the side and towards the upper part of the cell, 
though sometimes also connected with the stomach by means 
of a slender cord or funiculus, whilst the statoblasts are 
formed in or upon a similar funiculus or cord, which passes 
from the fundus of the stomach to the bottom of the cell, 
and upon which the testis, or male part of the generative 
system is developed. 
In two species of fresh-water Polyzoa, Plumatella emargi- 
nata and Alcyonella Benedeni, Professor Allman states that 
he has observed, besides the ordinary statoblasts, another 
kind, distinguished by some peculiarities. Whilst the ordi- 
nary statoblasts, towards the end of summer, may be observed 
lying loose in great numbers in the cavity of the cell, the 
peculiar kind in question “never lie loose in the cell, but are 
invariably attached to the internal surface of the walls, to 
which they are attached by a structureless cement.” After 
