For nearly 35 minutes it was a dog, but in the last five it was a finely-groomed thoroughbred, as Harvard's Jekyll-and-Hyde basketball team stunned Dartmouth, 71-69, at the IAB last night on supersub Mike Stenhouse's 17-foot jumper with two seconds left.

Stenhouse capped a hustling Crimson rally by snaring a loose ball near the leftside out-of-bounds line, taking two quick dribbles and sticking a jump shot over two falling Dartmouth defenders from the left side of the foul line to give Harvard its first lead of the game.

The Big Green's subsequent attempt at a full-court inbounds pass to their aptly-named star center Sterling Edmonds was foiled by a cluster of Harvard defenders, and--all of a sudden--this crazy game belonged to the Crimson.

The fairy-book finish was a pleasant close for what had been--until the last minutes--a less than pleasant 1978 finale. If the end of the contest was Cinderella at the ball, the first half and the opening minutes of the second were Cinderella the pauper.

To being with, Harvard's enigmatic star center Brian Banks did not show up for his last contest at the IAB--because of the flu, coach Frank McLaughlin would say after the game--although other sources said he was not seriously ill.

With Banks out of the line-up, Dartmouth's 6-ft. 9-in. Edmonds loomed taller than ever. Indeed, when the game started, Edmonds strutted his stuff to the tune of 16 first-half points as the Big Green cruised to a 30-17 lead in the first 15 minutes.

Harvard's first-half game had more turnovers than the pastry window at Elsie's, and the man-to-man defense looked like Swiss cheese as Dartmouth made uncontested lay-ups in bunches and threatened to turn the contest into a feast. Only Cy Booker's offense kept the home squad in the game.

Enter Dr. Jekyll, masquerading in uniform number 24 as Stenhouse, with five minutes to go in the stanza. Stenhouse teamed with Glenn Fine to crank up the Harvard offense and keep Harvard within range of Dartmouth at the intermission, 40-29.

McLaughlin's boys took the floor for the second-half warm-up looking like a bunch of first-year med students after their first autopsy--there was not the slightest hint of a smile on anyone's face, the probable result of some locker-room fireworks.

The fireworks in the second 20 minutes took place on the hardwood, however. After allowing Dartmouth to take charge and open a 50-36 margin in the first few minutes, the Crimson began to look like a squad for the first time all evening.

Seven points by Bob Hooft (16 on the night, to match nine rebounds) and a Cyrus Booker slam-dunk keyed a mini-comeback that brought the IAB residents to within five points, 50-45, at 14:00.

But that's when the momentum stopped, as both teams played erratically in the ensuing ten minutes and Dartmouth maintained a small but safe lead.

At the five - minute mark, the gap narrowed. Bobby Allen (12 points) hit an 18-footer; Fine (nine assists) laid one in off the break; and Allen hit another jumper to pull Harvard to within two, 69-67, at the 3:40 mark.

Iceman Stenhouse forced a backcourt violation to break Dartmouth's stall game at 2:40, then tied it at 69-all with a cool jumper from deep in the corner ten seconds later.

Following two quick possession switches, Harvard spread out its offense with two minutes left in an attempt to gain one last shot. Stenhouse was called on a dubious five-second violation at 0:47, but Gary Ackerman saved his tap on the ensuing jumpball to maintain Harvard possession.

Edmonds--the game's high scorer with 24--nearly saved it for the Big Green, tipping a Fine pass with ten seconds left, but then came Stenhouse, darting to save the ball and then arching the ball on its parabolic path to win it all.

It was pure class, and it made us all forget the rest of the game.

IAB INSIGHTS: Edmonds, a senior from Chesapeake, Va., inched toward third place on the all-time Dartmouth scoring list with his 24 points last night. The effort gave him 1277 career tallies, just 21 behind Larry Cubas '77. Dartmouth has two games remaining.

Harvard closes its schedule on the road this weekend against Yale and Brown. Bruin coach Gerry Alaimo resigned his post yesterday, effective after this weekend.