In what direction from the eyes are the =nostrils= (Fig. 211.) There are two pair of nostrils, but there is only one pair of nasal cavities, with two nostrils opening into each. There are no nasal passages to the mouth, as the test with a probe shows that the cavities do not open into the mouth. What two functions has the nose in man? What function has it in the fish? [Illustration: FIG. 210.BLACKBOARD OUTLINE OF FISH. ] There are _no external_ =ears=. The ear sacs are embedded in the bones of the skull. Is hearing acute or dull? When you are fishing, is it more necessary not to talk or to step lightly, so as not to jar the boat or bank?

[Illustration: FIG. 211.HEAD OF CARP. ] What is the use of the large openings found at the back of the head on each side? (Fig. 211.) Under the skin at the sides of the head are thin membrane bones formed from the skin; they aid the skin in protection. Just under these membrane bones are the gill covers, of true bone. Which consists of more parts, the membranous layer, or the true bony layer in the gill cover? (Figs. 211 and 212.) Is the =mouth= large or small? Are the _teeth_ blunt or pointed? Near the outer edge, or far in the mouth? (Fig. 212.) Does the fish have lips? Are the teeth in one continuous row in either jaw? In the upper jaw there are also teeth on the premaxillary bones. These bones are in front of the maxillary bones, which are without teeth. Teeth are also found in the roof of the mouth, and the tongue bears horny appendages similar to teeth. Are the teeth of the fish better suited for chewing or

Why are teeth on the tongue useful? Watch a fish eating: does it chew its food? Can a fish taste? Test by placing bits of brown paper and food in a vessel or jar containing a live fish. Is the throat, or gullet, of the fish large or small?

[Illustration: FIG. 212.SKELETON OF PERCH. ] The =skeleton= of a fish is simpler than the skeleton of other backboned animals. Study Fig. 212 or a prepared skeleton. At first glance, the skeleton appears to have two vertebral columns. Why? What bones does the fish have that correspond to bones in the human skeleton? Are the projections (processes) from the vertebr long or short? The _ribs_ are attached to the vertebr of the trunk, the last rib being above the vent. The tail begins at the vent. Are there more tail vertebr or trunk vertebr? Are there any neck (cervical) vertebr (_i.e._ in front of those that bear ribs)? The first few ribs (how many?) are attached to the central body of the vertebr. The remaining ribs are loosely attached to processes on the vertebr. The ribs of bony fishes are not homologous with the ribs of the higher vertebrates. In most fishes there are bones called intermuscular bones attached to the first ribs (how