122 PLANARIA. 
PLANARIA NIGRA.—Ova, Plate XV. Figs. 18, 19. 
The history of this animal is detailed in the Treatise on Planariz, 
1814. 
The ova are deposited chiefly on the neighbouring vegetable pro- 
ductions during September, and other seasons of the year. 
Puate XV. 
Fic. 18. Planaria nigra, ova, as deposited on a blade of grass. 
19. Group of ova, enlarged. 
Note.—The practical naturalist engaged in a course of observations, 
is frequently embarrassed by the appearance of animals having some re- 
semblance to the Planariz in several particulars, but without bemg able 
to identify them with the genus. 
a.—PLANARIA SERPENTINA, Plate XV. Fig. 20. 
Length between one and two lies; body flattened ; head obtuse, 
enlarging towards each side, and somewhat depressed in the centre of 
the front, where there seems a circular orifice, probably the mouth. The 
interanex, occupying much of the body, of a dark colour, and resembling 
curving or circular sacs. Colour of the animal white, or grey under the 
microscope. Motion smooth and gliding as that of other Planarizx. No 
eyes visible. Specimens were taken in July from the pools at Fenton 
Tower. 
PLATE XV. 
Fic. 20. Planaria serpentina, enlarged. 
b.—P.anoreEs Fusca.—Plate XVI. Figs. 35, 36. 
I have been at different times disposed to consider this minute 
marine animal allied to the Aplysia, or some other genus, always pre- 
suming that none of the specimens occurring were full-grown. But as 
