310 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 7 



Planktonic stages of what are believed to be this species have been 

 taken during April at La JoIIa. The 3-segmented larva has conspicuous 

 dark eyespots and paired black sti'ipes dorsally (pi. 48, fig. 49). Later 

 stages, up to a 19-segmented, have been taken from tows. One of the 

 later stages is shown in pi. 48, fig. 47. These larvae have modified spines 

 (pi. 48, fig. 48) in the fifth setiger as typical of the adult. 



P. ligni has been collected from Mission Bay (with P. citrona) north 

 to San Francisco Bay, especially from estuarine habitats. As P. amarincola 

 (Hartman, 1936, p. 49) it has been reported from Lake Merritt, Oak- 

 land, an inland arm of the sea with highly fluctuating salinity, especially 

 on the brackish side. Inclusion of these specimens with Webster's P. ligni 

 (1879) from New Jersey was first considered doubtful because of the 

 striking differences in size between the two. P. ligni was described as 

 measuring only 1 to 4 mm long; specimens from California measure 25 to 

 30 mm long. Since these studies were begun, it has been possible to exam- 

 ine not only Webster's types but also collections from other parts of 

 eastern America, and these all agree in morphological details with the 

 specimens from California ; individuals from North Carolina are approxi- 

 mately as large as those from southern California. 



Polydora socialis (Schmarda) 

 Plate 48, Figs. 41, 42 



Mesnil, 1896, pp. 193-194, pi. 12, figs. 30-32. 



Numerous collections from Mugu Lagoon, southern California, and 

 several from Point Richmond, San Francisco Bay, are referred to this 

 species. The former are much smaller than their more northern repre- 

 sentatives — their lengths only 8-10 mm as against 25-30 mm. At Mugu 

 Lagoon it forms extensive beds, over a muddy sand substratum, the soft, 

 gray, mucoid tubes lying over or near the surface, close to one another. 

 The specimens from San Francisco Bay were taken from a low, inter- 

 tidal eel grass bed. Originally described (1861) from Chile, this has 

 remained unknown except through Mesnil's redescription (1896) of the 

 type collection. This author concluded that this is "une espece surtout 

 voisine de P. caeca. Les ressemblances sont grandes, et les diiiferences 

 d'importance secondaire." Berkeley (1936, p. 468) has described a 

 subspecies, P. socialis plena from Nanaimo, British Columbia, which 

 differs from the stem form in having notosetae in the first segment. 



