The candidate cluster and protocluster catalog (CCPC) of
  spectroscopically identified structures spanning $2.74 < z < 3.71$
  We have developed a search methodology to identify galaxy protoclusters at
$z>2.74$, and implemented it on a sample of $\sim$14,000 galaxies with
previously measured redshifts. The results of this search are recorded in the
Candidate Cluster and Protocluster Catalog (CCPC). The catalog contains 12
clusters that are highly significant overdensities ($\delta_{gal}>7$), 6 of
which are previously known. We also identify another 31 candidate protoclusters
(including 4 previously identified structures) of lower overdensity. CCPC
systems vary over a wide range of physical sizes and shapes, from small,
compact groups to large, extended, and filamentary collections of galaxies.
This variety persists over the range from $z=3.71$ to $z=2.74$. These
structures exist as galaxy overdensities ($\delta_{gal}$) with a mean value of
2, similar to the values found for other protoclusters in the literature. The
median number of galaxies for CCPC systems is 11. Virial mass estimates are
large for these redshifts, with thirteen cases apparently having $M > 10^{15}\,
M_{\odot}$. If these systems are virialized, such masses would pose a challenge
to $\Lambda$CDM.
