414 
APPENDIX, 
body, the bristles on the ventral side, the orifices—mouth, re¬ 
productive, and anal—also the dorsal pores along the middle 
line of the back. Note the red line which marks the course of 
the dorsal blood-vessel. To examine the internal anatomy, lay 
the worm in a dish having a layer of beeswax in the bottom, 
slit open the body along the middle line of the dorsal surface, 
and separate the muscular walls of the body from the parts 
lying within, fastening back the flaps by pinning them to the 
beeswax. Keep the specimen covered with water if the worm 
be freshly killed, or with fifty per cent, alcohol if it be a pre¬ 
served specimen. Note the membranous partitions which sub¬ 
divide the large cavity of the body: the dorsal blood-vessel, 
lying along the top of the digestive system, around the anterior 
part of which are circular blood-vessels; the digestive system, 
consisting of the following principal parts : pharynx, gullet, 
crop, stomach, intestine, and along the top of the latter the so- 
called “ liver.” Along the sides of the anterior part of the di¬ 
gestive system look for the oesophageal glands and the repro¬ 
ductive glands. Slit open the alimentary canal and study its 
structure and contents. Look on the top of the anterior end of 
the pharynx for the brain. Remove the digestive system and, 
lying below it, look for the nerve chain of ganglia connected to 
the brain by nerve-threads encircling the pharynx. Make cross- 
sections of various parts of the body of hardened specimens and 
examine the structure. 
Mollusca. —-- The examination of a Snail is not easy, conse¬ 
quently the student would best use one of the Lamellibranchs, 
as the Clam or the Fresh-water Mussel. Put live clams in dishes 
of sea-water or mussels in fresh-water, the bottoms of the 
dishes being covered with a layer of sand three or four inches 
deep. Watch the animal crawl about and finally burv itself in 
the sand. Note the streams of water entering and leaving the 
siphons. Touch the tentacles at the margin of the siphons and 
note their sensitiveness. Of the anatomy, study first the shell 
-—its shape as seen from various directions, the covering or so- 
called “ epidermis,” the position of the hinge. Separate the 
two valves and remove the soft part of the body, noting where 
and how this is attached to the shell, how the valves are held 
together; examine the hinge-ligament and hinge-teeth, the mar¬ 
gin of the valves, and their thickness in various places. Note 
the scars left by the adductor muscles and the siphons (Fig. 
