A 19th-century political cartoonist coined the term gerrymander to describe a salamander-shaped legislative district contrived to favor the party of then-Massachusetts Gov. Elbridge Gerry. The word, which came to describe any molding of voting districts to favor particular candidates, retained its accusatory punch for centuries.

But like the closely related Newt, this salamander of yore has come to seem dated. Gerrymander is too quaint - cute, even, like something you could keep in a terrarium - to describe the monstrous forces that gave birth to Pennsylvania's new Seventh Congressional District.

Even a cursory glimpse will reveal that the Seventh is no vertebrate. If I had to compare it to a class of carbon-based life-forms, I'd probably go with the slime molds.

Slime molds, as it happens, were once classified with the fungi - an uncanny coincidence, since the Seventh, once a suburban Philadelphia district, now manages to extend into a prime mushroom-growing region on the Maryland border. Maryland, by the way, is one of three states the new district borders. It also spans five Pennsylvania counties and nearly 100 municipalities. And it divides more than a quarter of those generally small cities, townships, and boroughs among more than one congressional district - a practice that likely persuaded the commonwealth's highest court to throw out similarly contorted new state legislative districts last week.

Also coincidentally, slime molds have been posited as the biological basis for the organism that devours Downingtown in the 1958 horror movie The Blob. As for the Seventh District, it narrowly misses that Chester County borough in its oleaginous creep across the region.

From the urban outskirts of Philadelphia, the Seventh's metastatic dimensions - heedless of geography and conventional understandings of democracy - stretch in almost every direction. The district's northern reaches go clear to the Berks County community of Woodchoppertown, whose forefathers appear to have chosen its name to ensure that no one would ever be cynical enough to assign their representation to a Philadelphia pol. As The Inquirer reported, many of the people who live there are, like most Americans, not even sure what a "hoagie" is.

And then there's Bird-in-Hand, the heavily Amish community near Lancaster that's grasped by another of the district's tendrils - hence its newly proposed name, Bird-in-Tendril. The amoebic Seventh cares not that these pastures - and I use that word literally - are so alien to the crowded neighborhoods near Philadelphia International Airport. Its digestive juices coat commercial airliner and horse-and-buggy alike.

The Seventh's crazy gulfs, peninsulas, and isthmuses were designed to favor the Republican congressman who represents the district, Pat Meehan. But he and his party are incidental here: This kind of redistricting has become so commonplace and bipartisan that even the partisans are hard-pressed to pretend otherwise. In fact, Philadelphia party boss and Congressman Bob Brady was one of several Democrats who supported the redistricting plan.

Brady has been accused of doing so because the map makes his district more like him, which is to say white. One of his chief critics in this regard is a primary challenger, which is all Brady and most congressmen have to worry about these days. Because the increasing brazenness and sophistication of politically driven redistricting has made the overwhelming majority of districts safe for either Republicans or Democrats, most competition comes from within the parties. Therefore we have a nation of politicians wondering whether they are sufficiently extreme, even as we wonder why they are not accomplishing very much.

Our representatives, in short, are choosing their voters - which is exactly the opposite of how it was supposed to work.

So what should we do with the Seventh and its ilk? In The Blob, Downingtown's Lt. Dave has an excellent suggestion for the Air Force: "You should send us the biggest transport plane you have, and take this thing to the Arctic or somewhere, and drop it where it will never thaw."

E-mail Inquirer commentary editor Josh Gohlke at jgohlke@phillynews.com.