FOUND IN THE NORTHUMBERLAND LAKES. 415 
Fig. 6.—Egg after attachment to some foreign body much magnified, ex- 
hibiting chorion: aaa, a few of the mucus-globules contained 
in vesicles adhering to the egg. 
Fig. 7.—A few of the same vesicles containing mucus-globules more highly 
magnified. 
Prats VIII. 
Fig. 1.—Hydra much enlarged, exhibiting development of ova: a, basal 
portion of tentacles; 6, mouth; cc, sperm-vesicles; d, ovum 
considerably advanced; d, ovum just before it bursts through 
its envelope e. 
Fig. 2,—Much enlarged view of egg as it appears immediately after it has 
burst the envelope: a, egg; 0b, margins of envelope; cc, por- 
tions of the animal. 
Fig. 3.—A portion of Hydra much magnified, exhibiting the egg when 
ready to separate from parent: a, portion of the animal; 6, egg; 
cc, mucus globules as they at first appear; d, pedicle attaching 
egg to parent; ee, contracted margins of envelope. 
Fug. 4.—Enlarged view of Hydra much contracted, with egg attached, ex- 
hibiting anal orifice: a, mouth; 6, anal orifice as seen through 
the substanee of the adhesive disc; c, feces passing out of 
same; d, sperm vesicle; e, egg with undulated margins; 
J; pedicle attaching same to parent; g, contracted margin of 
envelope. 
Fig. 5.—Sperm vesicle much enlarged of the Hydra from the Northumber- 
land lakes: a, gland-like body within the base of same; 6, apex 
of same containing spermatozoa; cc, a portion of surface of 
animal. 
Fig. 6.—Sperm vesicle much enlarged of H. viridis: a, gland-like body 
within base of vesicle; b, apex of same containing spermatozoa; 
cc, surface of animal. 
Fig. 7—Much enlarged view of portion of tentacle of the flesh-coloured 
Hydra as seen in the compressor, exhibiting captor organs and 
organs of touch imbedded in the nodular enlargements: a, organs 
of touch; b, captor organs. 
Fig. 8.—Two of the organs of touch greatly magnified, exhibiting inner and 
outer vesicles and cilium. 
I’ig. 9.—Greatly enlarged view of retracted captor organ: a, outer vesicle ; 
6, arrow head with barbs depressed; c, membranous stalk of 
same; d, inner or lining membrane doubled down upon itself. 
Fig. 10.—Captor organ exserted: a, outer vesicle; 6, inner or lining mem- 
brane; c, membranous stalk supporting arrow head with the 
three barbs, c’, elevated; d, filament passing out of the pointed 
extremity of arrow head. 
Fig. 11.—Two enlarged views of elliptical sacs with filaments supposed to 
be poison organs cast from captor organ. 
G3 
