Extinct, It’s Not : Dinosaur Jr. is one of the most compelling college bands in the country. But songwriter J Mascis is not about to explain things.

It seemed appropriate that Dinosaur Jr., one of the country’s most compelling college/alternative rock bands, would pass through Los Angeles on a rare overcast day--this isn’t a group that has ever been known for a sunny disposition.

The trio’s cascading guitar assault often reflects the primal anxiety of a drowning man’s last, desperate gasp for air, all set against J Mascis’ themes about searching for something or someone to believe in--including a reason to believe in oneself. “There never really is a good time / There’s always nothing much to say” the group’s leader offers in one of the gentler, more melancholy tunes on the recent “Green Mind” album.

Mascis delivers the lines in the hesitant, almost retiring manner that has become his signature--a wavering, informal vocal style that Rolling Stone magazine has compared to someone trying unsuccessfully to persuade you he wasn’t asleep when you called.

The singer-guitarist-writer also seemed as if he was still trying to clear his head after a long sleep as he leaned back on a couch in a West Hollywood hotel room during a recent stopover. The Amherst, Mass.-based band was heading for Japan for a few shows before returning to California for concerts Friday at the Hollywood Palladium and Saturday at Iguanas in Tijuana.

At times, interviewing Mascis, 25, is a bit like throwing a ball to a dog and having the animal stare at it rather than chase it. When one writer complained at the end of a recent phone interview that Mascis hadn’t given her enough quotes to put together a story, he reportedly replied, “That’s your problem,” and hung up.

Don’t get the wrong idea: Mascis and his cohorts in Dinosaur Jr. aren’t sullen. They’re just, well, lethargic. Mascis, a soft-spoken couch potato whose metabolism seems to be permanently set in low gear, seems to enjoy nothing more than watching afternoon (or evening) TV. The curtains of the room on this day were pulled tight, blocking all traces of sunlight and the outside world.

The trait is apparently something that all the band members hold in common, one that has particularly intrigued the British pop press, which was the first to trumpet the band in the late ‘80s.

One of the few times, ironically, that Mascis did go after the ball during the interview was when the lethargic image was mentioned.

“People have to find something in your character to build a story around,” he said, a touch annoyed. “One person in England did it and then another and it just kept going. It’s not that I dislike doing interviews or that I try to be difficult, though I do find phone interviews hard.

“You don’t know the person you are talking to, but they think they know you from reading articles about you and they come at you from the weirdest angles. It’s not like a normal conversation. It’s a bizarre exchange and (I find) you don’t have much to say on that level.”

At the same time, Mascis tends to enjoy the hint of mystery that has grown up around the band.

“I’m not going out of my way to create an image or anything, but it is good when people have to use their imagination,” he said, sitting with drummer Murph, a sidekick since high school, and bassist Michael Johnson, who joined the group for this tour.

The mystery extends to the group’s lyrics, which examine the uncertainty and frustrations of relationships with a convincing and revealing youthful perspective. Though they are often hard to piece together on the record, Mascis refuses to include a lyric sheet in the album.

It’s an approach shared over the years by some of rock’s most acclaimed writers, including Bob Dylan and Elvis Costello. Mascis doesn’t write with the precision or literary edge of either, but he does frequently exhibit a poet’s insight and heart.

He also refused to clarify any of the lyrics during the interview--but he did exhibit a disarming sense of humor in the process.

Mascis was asked if these indeed are the right words from a song called “Blowin’ It”:

Well, I been thinking through the night

Everybody’s so uptight

People hurt and that’s their right

Cut ‘em all loose

Think I might . . .

Well, I don’t know one thing to say to you . . . .

Mascis smiled.

“Well . . . that’s close.”

Asked if a verse from another song was right, he smiled again.

“Not so close.”

Mascis first gained attention in hard-core rock circles as a guitar hero, and his playing--with its slashing, competing edges--does have an original and artful design. But it is his songwriting that makes Dinosaur Jr. so striking.

Lots of hard-core or alternative bands can express their alienation and desire solely through instrumental fury, but it’s doubly challenging to define those ideas in lyrics the way Mascis does. Even if occasional words are buried in the instrumental mix, the emotion in the songs is always evident.

In an earlier rock age, in fact, he--along with such contemporaries as the Replacements’ Paul Westerberg, Thelonious Monster’s Bob Forrest and the Gear Daddies’ Martin Zellar--might have walked on stage with an acoustic guitar in the singer-songwriter tradition of Dylan and John Prine.

But they picked up on rock at a time in the late ‘70s when the most exciting strains in the music were generated by the rowdy exclamation of the noisier-the-better punk movement--and Mascis, like the others, was inspired by it.

The son of a dentist, he grew up in Amherst listening to the music of his older brother, starting with the Beach Boys and proceeding through the Rolling Stones and Aerosmith. But it was the Sex Pistols that first spoke directly to him. Before he was even in his teens, Mascis started playing the drums because he loved the energy of it, pounding away for hours in the basement of the family home.

Even more than the Pistols, however, he identified with Eater, one of the many British punk bands that followed the Pistols. “I could relate to them because they were real young,” he recalled, wearing a baseball cap with Elvis Presley’s old “TCB” logo (for “Taking Care of Business”) on it. “They had this drummer who was 14 and they’d attack the Sex Pistols as too old. They did Alice Cooper’s ‘Eighteen,’ only they (renamed) it ‘Fifteen.’ ”

Also inspired by many of the American hard-core acts of the early ‘80s, Mascis started a group called Deep Wound, but later changed from drums to guitar and formed Dinosaur with Murph and another high school friend, bassist Lou Barlow. The trio released its first album in 1985 on Homestead Records, an independent New York label owned by another friend who went to college in Amherst.

But it wasn’t until a second album--”You’re Living All Over Me” on SST Records in 1987--and a trip to England that the group began attracting national attention on the college circuit for its dynamic, guitar-driven sound that was played at such ear-shattering volume live that some club owners reportedly made it clear that Dinosaur wasn’t welcome back. (The Jr. was added in 1987 after a San Francisco band pointed out that it had adopted the name first.)

After a second SST album, the band--reduced to a duo after a split with Barlow--signed with Sire Records and recorded “Green Mind.” It ended up pretty much a Mascis solo record, similar to the mostly Paul Westerberg Replacements album “All Shook Down.”

Mascis seems to have second thoughts about the solitary approach. He calls the album “fine,” but prefers the heightened attack of “You’re Living All Over Me.” Others may disagree. “Green Mind” is a more intimate and accessible album--one that expresses much the same youthful anxiety as “Living,” but in a way that reaches beyond the hard-core sect.

There were inevitable shouts of sellout when Dinosaur Jr. signed with Warner Bros.-distributed Sire, thus joining the ranks of other alternative bands--including R.E.M. and Sonic Youth--who have stepped from independent to major-label affiliations in recent years. But the reviews were mostly glowing and the album climbed to No. 3 in the weekly CMJ newsletter charts, which are based on college and alternative rock radio airplay.

In the opening track, “The Wagon,” Mascis defines the theme of miscommunication and searching that is at the heart of his work, echoing a bit of the mocking restlessness of Bob Dylan’s landmark “Like a Rolling Stone.”

So I’m fallin’

While you’re sailin’ on

Without a course in mind

Without a mind, without a dime

What is it that you wanna find?

Mascis--who still lives at his parents’ house in Amherst and is so little enthralled by the rock ‘n’ roll lifestyle that he hasn’t toured in almost two years--is often frustratingly understated about his accomplishments in “Green Mind” and in earlier albums, downplaying any talk of artistic ambition or goals. He even looks a bit puzzled when asked what rewards he gets from his music.

“It gives me something to do,” he said, after considerable prodding. “It’s not as boring as it would be pumping gas.”

He did, however, open up a bit on the subject of Neil Young, whose artistic independence he admires. Mascis even volunteered a favorite Young song: “Will to Love,” a quirky but endearing tune from the “American Stars and Bars” album that expresses unrelenting belief in someday finding an ideal love.

Talking again about his own music, Mascis brushed at his long, black hair.

“It’s not good to (spell) everything out in the songs,” he said hesitantly, also unsure of how much he should spell out in an interview. “I don’t like the way you can hear what (Michael Stipe) is saying now in R.E.M. records. I thought it was cool when you couldn’t really tell what he was talking about. Besides, I like it when people make up the words to suit their own needs. They can probably relate to the words they imagine a lot better at times than to the words that are really there.”

With some additional prodding he added: “I’ve got a very limited focus. Most of the songs are about trying to deal with people, which is a problem I think a lot of people have. In a way, it’s all like one big, continuous song . . . just seeing the same things from different angles or on different days.”