126 
by the palpable division of the body into a central (inner) 
and a peripheral (outer) layer ; and, secondly, by the peculiar 
structure of the pseudopods. Its central or inner mass 
consists of a sarcode body, which contains numerous true 
nucleated cells. On the other hand, the external sarcode 
encloses numerous closely pressed vacuoli, which give the 
entire outside an alveolar appearance. Each pseudopod 
consists of a firmer hyaline axis-substance, which proceeds 
from the inner portion, and of a thinner outer substance, 
full of moving granules, which envelopes the former. By 
these histological differences Actinosphaerium is already 
closely allied to the Radiolaria, from which it is, however, 
substantially different, as the cell-containing central mass is 
not separated from the peripheral sarcode by a special 
membrane (central capsule). At the same time, it is distin- 
guished from the true Actinophrys ( A.sol .) by those substantial 
differences which ally the latter by its homogeneous sarcode 
body closely to the Monera. In any case it is very unjusti- 
fiable to consider these two very distinct Protozoa as two 
different species of the one genus Actinophrys. Stein’s 
separation of the true Actinophrys (A. sot.) from the much 
higher organized Actino splicer ium ( Eichhornii ) is, under all 
circumstances, necessary. Actinosphaerium is a true Rliizo- 
pod, intermediate between the Acyttaria and the Radiolaria, 
and which I have therefore placed between both in my 
‘ General Morphology’ (vol. ii, p. xxviii) , as the representative 
of a particular (third) main division of the true Rhizopoda 
[Heliozoa ) . 
The viscous little star represented in figs. 23, 24, contains in 
its perfectly homogeneous sarcode body, neither the nucleus 
holding cells nor the bladder-like vacuoli of Actinosphaerium. 
The difference between an inner and outer layer in the tho- 
roughly homogeneous pseudopods is also wanting. Our 
Moner might rather be associated with the true Actinophrys 
(A. sot.) . But it does not possess the characteristic vacuoli (the 
large contraticle vesicles on the surface) of the latter, and is 
so especially distinguished by its peculiar reproduction that 
it is to be considered as the representative of a new genus, 
for which I propose the name Myxastrum. The species 
figured from Arrecife I call Myxastrum radians 
The granules which are scattered through the sarcode body 
of the Myxastrum are found in very different quantities, 
always in proportion to the amount of nourishment taken. 
In this respect Myxastrum conducts itself like Protomyxa 
and the true Rhizopoda. After a full meal, a large quantity 
of granules appear, which allow us to follow very clearly the 
