They call it Southern rock for a reason. Many reasons, actually — and none of them have anything to do with Connecticut.

Nonetheless, in 1978, when acts like the Allman Brothers, Lynyrd Skynyrd, the Marshall Tucker Band, Molly Hatchett and the Outlaws were international headliners, Mystic guitarist/vocalist Geoff Corkhill wanted to be a part of it all — or at least have a hell of a lot of fun trying. Along with two pals, guitarist Dan Ravenelle and guitarist/vocalist Jay Dempsey, they formed a Southern rock group called Franklin Lymestone.

"We started the band because we wanted to play music, and that's the music we were listening to," Corkhill says. He laughs. "To be honest, we weren't any good at it. I don't think we really knew we were inept, though, and, besides, we had long hair and that's all you really needed."

If Corkhill's assessment of the band's early-days talent level sounds harsh, it's also fair to say the average Southern rock band was extremely chops-heavy and, if the beginner's measuring stick is, oh, "The Allman Brothers Band at Fillmore East," well, that's a pretty steep learning curve.

Over the course of several years and through some personnel shifts, though, Franklin Lymestone got much better — sufficiently accomplished that they started filling regional clubs with their renditions of such dexterous mind-blowers from the repertoire as the Allmans' "Whipping Post" and the Outlaws' "Green Grass and High Tides." Before long, despite the fact they didn't focus on original material, they opened for authentic, south-of-the-Mason-Dixon-line heroes like .38 Special, Elvin Bishop and Grinderswitch.

Ultimately, Franklin Lymestone broke up shortly after the turn of the century. On Saturday, though, at Sneeker's Café in Groton, members from across the Franklin Lymestone timeline will gather for a 40th anniversary show.

"Forty's a pretty big reunion, as you get older and maybe have lost one or two people along the way," says Dempsey. "It's fun to get to do this, but this one takes on an added importance because of Geoff's situation."

He's referring to the fact that Corkhill, 60, is suffering from interstitial lung disease and is on a waiting list for a double lung transplant. In fact, when Corkhill speaks for the purpose of this story, he's at the Cleveland Clinic, where the operation will ultimately happen "when he gets the call," and he is undergoing one of the regular checkups prior to such a procedure. Corkhill's condition is sufficiently grim that he can't be at the reunion because the risk of infection in a crowd that size is too high.

"I can't play Saturday and, yeah, that bothers me a bit," Corkhill says. "But I have to do what I have to do. It would even be great to watch those guys play and sit there and have a beer. But I know they're going to sound great." He laughs again. "Maybe they needed that extra reason to finalize the show — and I'm it."

Interstitial lung disease, which has no known cause but may be associated with long-term exposure to hazardous materials or autoimmune disease, results in scarring that eventually affects the patient's ability to breathe and get enough oxygen into the bloodstream. There are no cures, though a successful transplant can prolong and improve the quality of life.

Corkhill, who lives with his wife, Kim, and daughter, Sabine, in Stonington, has never been a smoker but had his own business installing cable for years. He wonders if the structures or materials in some of the attics or basements he was in might have had a cumulative effect.

"I knew something was wrong seven years ago. Just little things, but they diagnosed it pretty quickly," he says. "I don't think I  understood the gravity because, early on, you might have a little difficulty breathing, but you still feel OK and you don't realize the reality of the progression of the disease."

The expenses for the double transplant — which include having to charter a plane whenever the call comes — are subtantial and long-term. In late July, Christopher's in Groton helped sponsore a charity golf tournament and raffle on behalf of the Corkhills, and it was wonderfully attended.

"I can't believe how thoughtful and generous people have been," Corkhill says. He pauses. "Actually, I can. I'm blessed to have friends and family and to live in a community like this. It's overwhelming. And, man, there's a lot of great players that are going to be there Saturday."

In addition to Dempsey, who plays regularly with his own Jay Dempsey Band, and Ravenelle, a member (with Corkhill) of the Village Jammers, ex-Lymestoners taking part will be: drummers/vocalists John Prentis (traveling from Florida), Bob Pia and Eric Wood; bassist/lead vocalist Mike Palazzolo; and guitarist/vocalist Billy Light. Palazzolo and Light are currently members of numerous ongoing local bands. Plenty of roadies, sound personnel and other area players will also be on hand in support.

When he heard the final lineup, Corkhill had a suggestion: "All three drummers? I don't know where they're gonna put them — but at least they should have a bowl of earplugs at the door."

That most of the participants are still musically active definitely helps in terms of mastering 40 songs of relatively difficult material after all these years.

"Well, we're supposed to have been rehearsing on our own for this," Dempsey laughs, "Then we graduated to weekly rehearsals and got a little nervous — so we had to kick up the intensity a bit. It's been a while since we played together."

In fact, the last Franklin Lymestone reunion was in 2000 — also at Sneekers. The impetus for that performance also had a melancholy undertone: it was a memorial for one-time Lymestone vocalist/harmonica player Rene Brisson.

"It's been nearly 20 years since Rene passed, and now Geoff's in a tough place — though obviously there's great hope with him being added to the transplant list," says Palazollo. "Geoff's one of the finest, funniest guys I've been blessed to know. To have the opportunity to help him on home turf with some good friends (playing) for good friends means more than I can express. There was a time when Franklin Lymestone was hungry for a local Saturday night gig. Rene and I approached a club owner who was a bit skeptical, but he took us on.

"Before the night was over, the coolers were empty, and the taps were dry. Hometown, man. We're gonna pull out the stops Saturday. Who's gonna join us?"

If you go

Who: Southern rock band Franklin Lymestone's 40th Reunion Concert

What: Benefitting founding member Geoff Corkhill, who needs a double lung transplant

When: 8 p.m. Saturday

Where: Sneeker's Cafe, 568 Poquonnock Rd., Groton

How much: Free; donations accepted and a raffle and plenty of merch from local bands associated with Lymestone members will be available

For more information: (860) 445-1967