e in the
second _Figure_ of the 31. _Scheme_, and in the little Mite-worm, which I
call a Land-crab, describ'd in the second Figure of the 33. _Scheme_, but
in their manner of generation being oviparous, &c. And it were very worthy
observation, whether there be not some kinds of transformation and
metamorphosis in the several states of _crustaceous_ water-animals, as
there is in several sorts of Insects; for if such could be met with, the
progress of the variations would be much more conspicuous in those larger
Animals, then they can be in any kind of Insects our colder Climate
affords.

These being their eyes, it affords us a very pretty Speculation to
contemplate their manner of vision, which, as it is very differing from
that of _biocular_ Animals, so is it not less admirable.

That each of these Pearls or _Hemispheres_ is a perfect eye, I think we
need not doubt, if we consider onely the outside or figure of any one of
them, for they being each of them cover'd with a transparent protuberant
_Cornea_, and containing a liquor within them, resembling the watry or
glassie humours of the eye, must necessarily refract all the parallel Rays
that fall on them out of the air, into a point not farr distant within
them, where (in all probability) the _Retina_ of the eye is placed, and
that opacous, dark, and mucous inward coat that (I formerly shew'd) I found
to subtend the concave part of the cluster is very likely to be that
_tunicle_ or coat, it appearing through the _Microscope_ to be plac'd a
little more than a Diameter of those Pearls below or within the _tunica
cornea_. And if so, then is there in all probability, a little Picture or
Image of the objects without, painted or made at the bottom of the _Retina_
against every one of those Pearls, so that there are as many impressions on
the _Retina_ or opacous skin, as there are Pearls or _Hemispheres_ on the
cluster. But because it is impossible for any protuberant surface
whatsoever, whether _sphaerial_ or other, so to refract the Rays that come
from farr remote _lateral_ points of any Object as to collect them again,
and unite them each in a distinct point, and that onely those Rays which
come from some point that lies in the _Axis_ of the Figure produc'd, are so
accurately refracted to one and the same point again, and that the
_lateral_ Rays, the further they are remov'd, the more imperfect is their
refracted confluence; It follows therefore, that onely the Picture of