ZOOLOGICAL EXERCISES. 
side. Behind this, on the left, is a portion of 
the stomach, yellowish, or perhaps coloured green 
with its food. On the right, and lying on the 
stomach, are the purplish white reproductive organs. 
Behind them, in the median line, is the coiled intes- 
tine, colourless, or filled with green or brown vegetable 
matter; the brown liver, and the deep purple ovo- 
testis. To the right is the opaque, yellowish, renal 
organ, lying in the pulmonary chamber. Notice the 
aorta passing from the pulmonary chamber through 
a sharp fold in the intestine. The retractor muscle 
of the head passing from behind the pulmonary 
chamber through the folds of the reproductive 
organs ; and the retractor of the penis, arising Just 
before the pulmonary chamber. | 
4, Cut open the floor of the pulmonary chamber ; observe 
the pale white pyriform heart, lying in the anterior 
concavity of the renal organ. It consists of a ven- 
tricle and an auricle, and from the former leads the 
aorta which has been already seen. Turn it on one 
side, and from below extract the semi-transparent 
shell. Examine a portion of the renal organ with 
the quarter objective ; notice the numerous concre- 
tions. 
5. Alimentary system.—Notice the rectum going from 
just in front of the ovo-testis to the anus, situated in 
the pulmonary chamber. Cut it and the aorta. 
Turn back (i.¢., to the left) the fold of the intestime 
that was held down by the aorta; below it, in the 
centre, will be seen a dead-white vessel—the her- 
maphrodite duct—leading from the ovo-testis to the 
oviduct. Carefully separate the alimentary system 
from the reproductive system ; turn the latter forward, 
