Bob and Jack

Sesame Street composer-lyricist Moss and illustrator Demarest ( My Little Red Car ; No Peas for Nellie ) team up again (as they did in The Butterfly Jar ) with this droll saga of a boy named Jack, ``who more than anything wanted a yak.'' Rhyming couplets and sprightly line drawings deftly present the many adventures of this oddly touching odd couple. The story begins in grade school, continues on through college (``I wish you could come, but I won't get my wish. / They just allow hamsters and tropical fish''), Bob's death, Jack's marriage and eventual family--and finally comes full circle, with Jack presenting his own daughter with a yak of her own (she names him Steve). Although the book doesn't have quite the zany charm of Dr. Seuss's books, its eminent readability and sweet message about the continuity of life will find it an enthusiastic audience. All ages. (Oct.)