Healthy City Board of Educ. v. Doyle, 429 U.S. 274, 280, 97 S.Ct. 568, 572, 50 L.Ed.2d 471 (1977), the Court characterized the relevant issue as whether the School Board defendant there was to be treated as an arm of the State partaking of the State's Eleventh Amendment immunity, or . . . as a municipal corporation or other political subdivision to which the Eleventh Amendment does not extend.