"In the high school halls/ In the shopping malls/ Conform or be cast out," goes the song "Subdivisions," from the latest album by the Canadian rock trio Rush. Sentiments like these, which mark the quintessence of solemn teen-age angst in contemporary rock, are one reason that Rush is so phenomenally popular with adolescents. This popularity was demonstrated Thursday in Madison Square Garden, where Rush opened a sold-out two-night stand. "Subdivisions" was greeted with enthusiastic recognition by a very young and adoring crowd.

Like its message -- a mixture of psychadelicized science-fiction and grim social determinism -- Rush's music is appropirately bombastic. The band's characteristic tunes are modal blues fragments elongated and sweetened with arty, even romantic, flourishes. Geddy Lee is the lead singer and bassist and his tenor yelps find a comfortable middle ground between the aggressiveness of English heavy metal and the softer English art rock.

Instrumentally, Rush's strongest asset is its drummer-lyricist Neil Peart, whose bag of tricks runs from goose-stepping heavy-metal patterns to hard-rock reggae. While Thursday's concert offered a more convincing case for Rush than any album, the music still seemed an entirely unoriginal blend of heavy-metal and art-rock borrowings attached to unmemorable tunes.