The Descent of Man

the satisfaction of seeing, in April, 1833, and
therefore some years before any other naturalist,
the locomotive larvae of a compound Ascidian,
closely allied to Synoicum, but apparently
generically distinct from it. The tail was about
five times as long as the oblong head, and terminated
in a very fine filament. It was, as sketched
by me under a simple microscope, plainly
divided by transverse opaque partitions, which
I presume represent the great cells figured by
Kovalevsky. At an early stage of development
the tail was closely coiled round the head of the
larva.), and have the power of swimming freely
about. Mr. Kovalevsky (24. 'Memoires de l'Acad.
des Sciences de St. Petersbourg,' tom. x.
No. 15, 1866.) has lately observed that the larvae
of Ascidians are related to the Vertebrata,
in their manner of development, in the relative
position of the nervous system, and in possessing
a structure closely like the chorda dorsalis
of vertebrate animals; and in this he has been
since confirmed by Prof. Kupffer. M. Kovalevs-