Massachusetts' hopes for an effective express transit system to the South Shore and perhaps Harvard's designs for the Bennett St. MTA yards quite suddenly began to look futile yesterday. The State Senate finally rejected Governor Volpe's plan to purchase the Old Colony Line of the New Haven Railroad.

The Senate voted 19 to 21 not to reconsider its Tuesday action in defeating the bill to take up the state's purchase option which expired last night. The bill was one of several introduced by Volpe in an attempt to bring order out of chaos in the Boston transit system.

The bill would have authorized the Commonwealth to buy the ailing line from the deficit-ridden New Haven for what constitutes salvage rates, a low $1,159,000. It was part of he Governor's plan to link up the services of the Old Colony and the MTA and thus provide an extensive system for the South Shore.

To forestall opposition from area legislators whose municipalities now pay heavily for the present MTA deficit, Volpe had emphasized that he would not ask that the financial operations of the two be combined. In any case, it appears that Senators from outside the Metropolitan area defeated the bill.

Although sources at the State House said that a move was a foot to revive the legislation, chances of its success seemed dubious last night. This was the second time in six months that the Senate failed to act on the issue.

After the Great and General Court voted down the bill on December 8, Judge Robert K. Anderson of the New Haven Federal District Court extended the deadline for execution of the option to May 3, yesterday, Anderson has said he will not grant another extension.

Defeat of the bill may also hamper the University's chances of obtaining the MTA yards across from Eliot and Kirkland Houses, where Harvard would locate the tenth House called for in the Program for Harvard College. It was reported last fall that the Old Colony had storage facilities which the MTA could have substituted for its Cambridge yards