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A catalog of 732 optically selected, nearby poor clusters of galaxies covering the entire sky north of −3 • declination is presented. The poor clusters, called WBL clusters, were identified as concentrations of 3 or more galaxies with photographic magnitudes brighter than 15.7, possessing a galaxy surface overdensity of 10 4/3 . These criteria are consistent with those used in the identification of the original Yerkes poor clusters, and this new catalog substantially increases the sample size of such objects. These poor clusters cover the entire range of galaxy associations up to and including Abell clusters, systematically including poor and rich galaxy systems spanning over three orders of magnitude in the cluster mass function. As a result, this new catalog contains a greater diversity of richness and structures than other group catalogs, such as the Hickson or Yerkes catalogs. The information on individual galaxies includes

We analyze the filamentarity in the Las Campanas redshift survey (LCRS) and determine the length scale at which filaments are statistically significant. The largest length scale at which filaments are statistically significant, real objects is between 70 and 80 h À1 Mpc for the LCRS À3 slice. Filamentary features longer than 80 h À1 Mpc, although identified, are not statistically significant; they arise from chance alignments. For the five other LCRS slices, filaments of lengths 50-70 h À1 Mpc are statistically significant, but not beyond. These results indicate that while individual filaments up to 80 h À1 Mpc are statistically significant, the impression of structure on larger scales is a visual effect. On scales larger than 80 h À1 Mpc, the filaments interconnect by statistical chance to form the filament-void network. The reality of the 80 h À1 Mpc features in the À3 slice makes them the longest coherent features in the LCRS. While filaments are a natural outcome of gravitational instability, any numerical model that attempts to describe the formation of large-scale structure in the universe must produce coherent structures on scales that match these observations.

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