What is the test for naming a defendant in a civil rights action brought under the Civil Rights Act?

This action, brought under the Civil Rights Act (42 U.S.C. 1983) was filed on August 17, 1973. Suitably decorated as a civil rights complaint, ⁵ it pleads, in the main, the facts later alleged in Levy III. ⁶ Neither the City nor the County, the two public agencies before us, was named as a defendant. Under the law as it was thought to be at the time (Moor v. County of Alameda (1973) 411 U.S. 693, 715, 93 S.Ct. 1785, 36 L.Ed.2d 596; Monroe v. Pape (1961) 365 U.S. 167, 187-192, 81 S.Ct. 473, 5 L.Ed.2d 492) any attempt to name either entity would have been quixotic. ⁷