182 DR. BEALE, ON CONTRACTILITY. 
separated by its much smaller size, by the entire absence of 
a constriction, by its elliptic form, and by its smooth, not 
punctate, cell-membrane. 
From all these, and every other member of the family, it 
is, moreover, further distinguished by the remarkable form of 
its zygospore. It is possible that this may in some measure 
agree in nature with that of Tetmemorus levis, Ralfs; but 
even if found isolated, it could not be mistaken for that of 
that species, differing, as it does, in form and size therefrom. 
But, as before stated, this plant is no Tetmemorus, wanting, 
as it does, a terminal notch and central constriction. I say 
it is possible that the quadrate, or cruciately-lobed zygospore 
of this species, may agree in nature with that of 7. levis ; but 
although there is in all my specimens of the new Penium a 
tendency in the cell-contents of the zygospore to become 
collected towards the middle, I have not once noticed the 
formation of an inner coat, as happens in 7. levis. Yet it 
may have been that my specimens were not sufficiently 
matured. We are here, too, reminded of the zygospore in 
Closterium Cornu and others, Stauroceras, Kiitz.; but even if 
found isolated, the zygospores never could by possibility be 
mistaken the one for the other. There is the common cir- 
cumstance, however, that the parent cell-membranes remain 
persistently attached to the zygospore. Thus this little 
Penium possibly points out new cross affinities, to Tetme- 
morus on the one hand (although, as is well known, in that 
genus dwo forms of zygospore occur, as indeed this new form 
proves for the genus Penium), and to certain species of Clo- 
sterium on the other. 
It affords me great pleasure indeed to avail myself of the 
opportunity to name so distinct a species after David Moore, 
Ph.D., F.L.8., M.R.LA., &c., of the Glasnevin Botanic 
Garden, not only as a token, inadequate though it be, of 
respect for that gentleman’s high scientific attainments and 
of my personal esteem for himself, but also as commemorative 
of a very agreeable little excursion, when we had each the 
pleasure to be of the party, on which occasion I first gathered 
Pentium Mooreanum. 
On “ContrRactiLity”’ as distinguished from puRELY VITAL 
Movements. By Lionet S. Bearz, M.B., F.R.S. 
Tere are probably few actions more different than the 
contraction of a muscle or the vibration of cilia, and the move- 
ments which occur in a living Ameeba, in a living mucus: 
