4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 119 



only on coastal slopes in depths exceeding 120 m. These communities 

 have not been sampled frequently in southern California because of 

 steeply sloping bottoms and diffuse sampling grids. 



The headland of Monterey Peninsula has a rocky substrate but to 

 the northeast a long, slightly concave shoreline is composed of sand 

 beach. A community dominated by the polychaete Nothria species 

 occurs on inshore sand bottoms in depths of less than 30 m ; presumably 

 it is similar to that described from southern California by Barnard 

 (1963). 



The Amphipod Fauna 



Because most of the Monterey shelf lies in depths exceeding 50 m, 

 the station grid embraces only 13 samples in depths of 10 to 50 m. 

 Those few samples have little comparative significance to samples 

 from southern California. Thus, this discussion is confined to the 

 33 samples from depths of 50 to 139 m. The Amphipoda occurring 

 in Monterey Bay are listed in rank in table 2, with their frequencies 

 of individuals and their limitations to depths of 50 to 139 m. They 

 are compared with rankings of species from similar depths in southern 

 California (tables 3, 4, 5, 6). 



Half of the 20 most abundant species occurring in southern Cali- 

 fornian depths of 94-183 m (table 6) also occur in the first 20 of 

 Monterey Bay in depths of 50-139 m (table 2). Those southern 

 CaUfornia species not found in the list of abundant Monterey species 

 are Ampelisca pacijica, Westwoodilla caecula, Ampelisca brevisimulata, 

 Orchomene decipiens, Nicippe tumida, Ampelisca pugetica, Lysianassa 

 holmesi, Paraphoxus robustus, Pardisynopia synopiae, and Lysianassa 

 oculata (the latter is number 22 in Monterey Bay). Because all of 

 those species do occur in low frequency in Monterey Bay, this poor 

 comparison is probably a circumstance of low sampling frequency. 

 These data also indicate that shallow waters of Monterey Bay, de- 

 spite the occurrence of upwelling, are too warm for the occurrence 

 of deep-water species. 



A 50 percent correspondence in predominant species occurring 

 both on the Monterey deep shelf and in southern California depths of 

 75 to 92 m also occurs (table 5). Some deep-water species, i.e., 

 Nicippe tumida and Pardisynopia synopiae, occur dominantly in the 

 southern California section but not in Monterey Bay. 



Only 8 of the 20 predominant species occurring in depths of 57 to 

 73 m also predominate in Monterey Bay. Similarly, neither Nicippe 

 tumida nor Urothoe varvarini are abundant in Monterey Bay (table 4). 

 The same is true in depths of 39 to 55 m (table 3). 



These poor faunal congruencies may result from the low densities 

 of the individual species in the Monterey samples. For instance, 



