Step 15: Darken the arc on the top, right side of the head for the Boston terrier's first ear. Inside the shape, along the bottom, draw a series of short, curved lines for the inner structure of the ear. These lines don't have to be perfect. Draw longer lines on the edges of the shape, near the top.
Step 16: Use the arc on the left as a guide to draw the Boston terrier's other ear the same way. Don't draw as many lines for structure along the bottom because the dog's head will be partly blocking the ear.
Step 17: Use the big initial circle as a guide to draw the rest of the dog's head. On the left side, draw a wavy line that's closer to the eye to make the shape of the head narrower than the circle. Draw a short, curved line over each eye to emphasize the thick brows. Add a few more short lines within the Boston terrier's head to give it more shape and structure.
Step 18: Use the second line from the left as a guide to draw the first front leg. Follow the path of the guide and lightly sketch the shape of the dog's leg around it. The top part of the shape should be wide and the bottom narrow. Bend the leg to indicate the joints. At the bottom, draw a couple of curved lines with small, triangular shapes on the tips for the toes and nails. Darken the rest of the Boston terrier's leg. Keep the edges of the shape close to the guide so that the leg isn't too wide.
Step 19: Use the line on the left as a guide to draw the dog's other front leg the same way. This leg should look similar to the first one, only smaller. Sketch lightly at first as you draw around the guide. Bend the leg near the bottom for the joints. When you get the shape right, darken the lines. Use a couple of short, curved lines at the bottom for the Boston terrier's toes and tiny triangular shapes for the nails. A portion of this leg at the top will be behind the body.