The head is not separated from the rest of the body, as in insects, but forms, with the thorax, one piece. On the front of the head are eight eyes, Q, which are differently arranged in different spiders. On the abdomen are several pairs of dark smooth spots, which mark the ends of muscles extending downward through the abdomen. The markings of this spider are very complicated. The spot on the middle of the front of the abdomen is a very common one, and, in some spiders, extends the whole length of the body. The waved lines on each side are also common, and, in long-bodied spiders, often form two bright-colored stripes, or rows of spots, running nearly straight the whole length of the abdomen.