1918] Essenherg: Distrihidion of the Polyitoidae 111 



Considering the species with reference to distribution in the dif- 

 ferent zones we get the results shown in table 2. 



As is shown in table 2 there are eleven exclusively subboreal species 

 of Polynoidae. Four species are common to the lower boreal and north 

 temperate zones. Of these, Polynoe lordi is more abundant in the 

 lower boreal zone, occurring very rarely in the northern part of the 

 north temperate. There are ten exclusively north temperate species, 

 and eighteen exclusively subtropical species. Polynoe calif ornica 

 really belongs to the latter zone but occasional specimens of it have 

 been found in the southern part of the north temperate zone. Four 

 of the species are found in all zones. Tm^o of these are the cosmopoli- 

 tans Harmothoe imhricata and Lepidonotus squamatus and the two 

 others are the American species Halosydna insignis and Lepidonotus 

 caeloris. 



In some cases the individuals of a species are very few in number, 

 at least in collections, and again many species are abundantly repre- 

 sented. However, these species are always found in their particular 

 zones as has been shown before and are limited to very small areas. 

 Examples of these are Polynoe fragilis and Polynoe lordi. These have 

 been recorded thus far only from the coastal area included between 

 Alaska and San Francisco Bay. Harmothoe tuta is seemingly re- 

 stricted to the northern part of the lower boreal region, its existence 

 being known only at Puget Sound and Sitka. A great number of 

 species of Polynoidae inhabiting this coast are limited to the southern 

 part of the coast of California. Among these are Lepidasthenia gigas, 

 Polynoe calif ornica and Harmothoe hirsuta. They occupy a compara- 

 tively small area along the coast from San Pedro to San Diego. A 

 number of other species, namely, Harmothoe triannulata, Harmothoe 

 fragilis, Polynoe remigata, and Polynoe filamentosa, have been found 

 thus far only around the islands west' of San Diego. Some of these 

 species are known to occur only at considerable depths. Areas of 

 intensive collecting doubtless influence these apparent limitations to 

 some extent. 



