Using data recorded with the CLEO II and CLEO ILV detector configurations a
t the Cornell Electron Storage Rings, we report the first observation and m
ass measurement of the Sigma (c)*(+) charmed baryon, and an updated measure
ment of the mass of the Sigma (+)(c) baryon. We find M(Sigma (c)*(+)) - M(L
ambda (+)(c)) = (231.0 +/- 1.1 +/- 2.0) MeV, and M(Sigma (+)(c)) - M(Lambda
(+)(c)) = (166.4 +/- 0.2 +/- 0.3) MeV, where the errors are statistical an
d systematic, respectively.