Jacob is moving the entire clan to Egypt and Genesis stops here for another of those endless lists of who is going along. Except, that it isn't so endless when you realize the significance of the numbers ... then it becomes very interesting.
The author of Genesis takes the occasion of this move to Egypt to record a list of all the descendants of Jacob. To the Hebrews, 70 was the ideal and complete number: it is the number of descendants of Noah after the flood, corresponding in the ancient world to the 70 nations of the world; it's also the number of elders of Israel and of the disciples of Jesus...All quoted material is from Catholic Exchange's "Catholic Scripture Study." See the sidebar under "Bible Study: Genesis" for links to references used.
Not long ago, the family was just Jacob and Rachel and Leah. Now they are 70: the number of completeness, suggesting a complete development in God's plan. Why is this list here? This is the rootstock of the nation of Israel. As there are 70 nations in the world, there are 70 tribal units in Israel. Later on when Moses records all the family groups of the new nation, no one is mentioned who is not on this list. God is accomplishing His plan to form a nation, and we see here that the foundation has been laid.
[To come up with 70, the author takes out Judah's two dead sons (vs. 12) and adds in Joseph and his two sons already in Egypt and Jacob himself. He ignores the entire third generation except for Joseph's sons, who will become heads of two tribes in Joseph's place. The total is not "the descendants of Israel, who came into Egypt (vs. 8)" on that particular trip, but all the family who ended up settling in Egypt.]