' 
PLANARIA. 105 
/ 
ing characteristics of some others are more feebly imprinted, so that it 
is frequently doubtful whether they are not merely varieties. Thus, I 
would be rather understood to offer the following observations as general 
illustrations of the nature of the genus ; at least until better opportu- 
nities shall enable the observer to ascertain the complete and absolute 
distinction of species. 
The Planaria maculata extends six lines in length, by nearly three 
in breadth ; both extremities very obtuse. Four clusters of minute 
black specks are on the upper surface, at some distance behind the an- 
terior extremity. The posterior clusters consist of about ten specks each ; 
the anterior clusters are more diffuse, and the specks sometimes. so much 
dispersed as to lose that character. The former are not seated ona 
lighter ground, as in the Planaria flewilis. This Planaria is wholly spot- 
ted or speckled with chesnut-brown, on a ground of wood-brown. 
The only difference I have been able to recognise between it and the 
Planaria flewilis, consists in the uniformly greater obtuseness of the ex- 
tremities, especially of the lower extremity ; and if there be any distinc- 
tion between this species and the atomata, it seems to consist in the finer 
and more minute speckling of the latter. There is no speckling of the 
Hlewilis, that of the maculata is occasionally very dark. 
Spawn is deposited from August until December, and always in 
quadrangular patches of ova, amidst slight adhesive albumenous matter. 
A patch produced in December, consisted of about 100 ova, each rather 
a flattened sphere, including a single embryo, which, in advancing to- 
wards maturity, performs a very slow revolution around the interior of 
its prison, such as, with some, to require ten or twelve seconds to com- 
plete the circle, and with others half as long. This will recall, very for- 
cibly, a similar revolution or circuit, beheld in some of the embryonic 
Gasteropodes. August is the chief breeding season. The spawning is 
not confined to a single patch ; and after the first, a considerable interval 
may elapse before the second appears. 
These creatures dwell under stones, especially if of considerable size, 
at about half tide. I have not observed them seek to lodge under any of 
small dimensions. They prefer a flat smooth surface. 
0) 
