NO. 2 HARTMAN : POLYCHAETOUS ANNELIDS 243 



95. Eudistylia vancouveri (Kinberg) 



96. Pseudopotamilla occelata Moore 



97. Pseudopotamilla socialis, new species 



Family Serpulidae 



98. Cruciffera zyffophora (Johnson) 



99. Serpula vermicularis Linnaeus 

 100. Dexiospira spirillum (Linnaeus) 

 lOL Laeospira borealis {Dz.\xd\n) 



The most practical reference for the nonspecialist continues to be 

 Fauvel (1923, 1927, Faune de France). This gives excellent diagnoses 

 and figures of many genera, although many occurring in the eastern Pacific 

 are not included. American species, also, differ widely from the Euro- 

 pean ones, except for a few which may be regarded cosmopolitan in 

 distribution. An effort has been made herein to refer either to an illus- 

 trated or to a diagnostic description for each species. It is hoped that the 

 student will not rely only on the keys given below but will consult a more 

 complete account for more certain identification. Measurements given 

 are only approximate and are based largely on mature individuals. 



Family Polynoidae 

 Key to Species 



1. With 12 pairs of elytra, their surface more or less tubercled . . 



Lepidonotus caelorus 



1. With 15 pairs of elytra, these more or less easily detached . . 3 



Harmotho'e 



1. With 18 pairs of elytra, these more or less firmly attached; free 



living or commensal Halosydna brevisetosa 



1. With more than 20 pairs of elytra, the last few pairs noticeably 

 smaller than those preceding ; usually pale in life ; typically com- 

 mensal Arctonoe 2 



2. Elytra ruffled at their outer margins, usually reddish or yellow 

 in life; commensal with asteroids A. fragilis 



2. Elytra nearly or quite smooth, pale or somewhat fuscus; com- 

 mensal with moUusks, echinoderms, and other organisms, rarely 

 free living A. vittata 



3. Larger, typically over 20 mm long ; free living ; first pair of elytra 

 usually pale, others dark H. imbricata 



3. Usually smaller, typically less than 20 mm long; commensal with 

 leptosynaptids ; elytra pale except for a dark spot near the center 

 H. lunulata 



