372 Agassiz on the Relations between Animals 
among Entomostraca, while others have considered them as more 
closely allied to worms. But I may say that all, or almost all, 
naturalists at present understand the necessity of removing them 
from among Radiata into the great type of Articulata. 
This point is no longer in question; the only remaining doubt 
respecting them is whether they should rank among the lower 
Crustacea, or among the worms in the wider sense. As for the Pol- 
ygastrica, we meet with greater difficulties in attempting to classify 
them ; for this group, as understood by Ehrenberg, consists still 
of most heterogeneous beings which do not even all belong to the 
animal kingdom. Recent investigations upon the so-called An- 
entera, including the families of Baccillaria and Volvocine Infu- 
soria, have satisfactorily shown, in my opinion, and in that of most 
competent observers, that this type of Ehrenberg’s Polygastrica 
without gastric cavities, and without an alimentary tube, are really 
plants belonging to the order of Alge in the widest extension of 
this group; while most of the Monas tribe are mérely movable 
erms of various kinds of other Algee. As for the other Polygas- 
trica which Ehrenberg combines in this division of Enterodela, I 
am satisfied that they also constitute still a heterogeneous group 
belonging to different types of the animal kingdom; and that 
most of them, far from being perfect animals, are only germs in 
an early state of development. The family of Vorticellee exhibits 
so close a relation with the Bryozoa, and especially with the genus 
Pedicellina, that I have no doubt that wherever Bryozoa should 
be placed, Vorticella should follow, and be ranked in the same 
division with them. ; 
The last group of Infusoria, Bursaria, Paramecium and the like, 
are, as I have satisfied myself by direct investigation, germs of 
fresh water worms, some of which I have seen hatched from eggs 
of Planaria laid under my eyes. This being the case, we see that, 
without exception, the whole class of so-called Infusoria must be 
dissolved into its various elements and divided partly among the 
Articulata, and partly among Mollusca in the widest extension of 
those groups, (if it can be shown that Bryozoa belongs also to the 
type of Mollusea,) that large numbers of them belong to the veg- 
etable kingdom, and others are simply germs of other types, and 
at no single one of them belongs to the type of Radiata. — 
weet ae 
& 
Pe 
