"The next book will be written by Dory Shannon," the author announces at the end of the prose odyssey that is somewhat less than half of this curiously schizophrenic book. This decision is a triumph of sorts for one who has called herself "a shadowless being," a reflection of others who has no reflection of her own. No longer will she be known by the name of the man who denied he was her father or the man who stopped being her husband, but by the name of her mother, which is also the name of a river. If it is still a reflection, it is at least positive.

Like all the reflections in "Bog-Trotter," the one on names is fragmented, scattered through the book in bits and pieces, popping up haphazardly here and there before reaching its resolution. This is a book of fragments -- some fascinating and beautifully wrought, others repellent or even downright scary. The fascination and the repulsion are both based on the book's unusual opportunity for readers: a chance to look closely at another person's madness.

The subtitle is misleading; "Bog-Trotter" is not really "An Autobiography with Lyrics" but rather a collection of lyrics (including some of the best in contemporary popular song) preceded by a fragmentary autobiographical commentary. Like the lyrics, the prose deals with several obsessive topics, centering on Previn's (or Shannon's) precarious grasp of a fragile idenity. And occasionally, the prose in the front of the book is more effective than the verse counterpart found among the lyrics in the back.

But like the identity, the prose is fitful, uneven, often insecure. As a writer of lyrics, Previn is a professional; the lines are always singable and frequently more effective when heard with music (the writing of lyrics is a demanding but incomplete art). But often the songs have a depth bellied by their easy-moving grace. Having identified the personal themes, one is amazed at how the writer has been able to work them into movie soundtracks without leaving any clue to what she is doing.

"In the mirror 'we look as we pass/ no reflection's revealed/in the glass.' Those words may describe Marlon Brando in "Last Tango in Paris," but they also project one of Dory Previn's basic images of herself.

"Where will i/ how will i/ think of my name" may be thematic in the "Valley of the Dolls" soundtrack, but it's also Dory what's-her-name voicing one of her private concerns.

"I'll hold/the child i never held/ in a place/ called yesterday" projects the lyricist remarkably into the title role of "Goodbye Mr. Chips." It takes a very special kind of talent to be paid well for self-expression in a medium as depersonalized (at least for the writer) as a big Hollywood film, and Previn clearly has that talent.

But her ability to manipulate a manipulative industry is not the author's chief claim to attention, and the quality of her writing suffers when she is projecting her own image into that inhospitable medium. The "private" songs are, on the whole, better than the ones for soundtracks , and they are the primary reason why an average reader might want to look into this book -- certainly a stronger reason than the occasional references to Andre Previn, her former husband, and Mia Farrow, her successor in the temporary role of Mrs. Previn. To Andre, she is gentle ("He left me for another woman long after I had deserted him for another reality . . . To this day, I don't know how he stayed so long."); to Mia Farrow, she is a bit more harsh, but that is partly because Farrow publicly criticized one of her best songs.

These private glimpses of spectacularly public episodes are, however, only a very small fraction of the book's contents -- readable in a few minutes, once they are tracked down in the rambling, curiously disorganized text. The bulk of the book, and its primary interest, lies in its account of the writer's journey into and through madness. She takes the reader into wild, strange landscapes of the mind -- places where we would swear we have never been before. And once in a while, with a few precise, honest words, she makes some detail of the distorted contents of her dreams and memories look curiously familiar.

One could wish that she had written a better-organized book, an easier book to read. As it stands, "Bog-Trotter" is more a therapeutic exercise for the author than a pastime for the casual reader. Its best part is the collection of song texts (more than 200 pages of them) at the end. In the prose section, there are flashes of illumination, but they come fitfully and they are embedded in masses of material almost too private, too specialized to be publishable.