FAMILY ARENICOLIDAE 



Only one genus and species known from Records. — Cape Hatteras to Beaufort (1, 5, 



North^Carolina. 7.11,13,18,*). 



„ . Difitrihiitioii. — Massachusetts to the West In- 



Arenicola cristata St.mpson, I85b ^-^^^ ^^^^ ^f ^^^.^^^ ^^^ California; burrows in 



Arenicohi cristata. - Wells, 1961: 10, pi. 1-4; muddy .sand on sheltered beaches. 



1962: 333, pi. 1. 2. - Hartman, 1969: 415, 

 Fig. 1. 



FAMILY CAPITELLIDAE 

 Key to genera and species 



Note. — Generic distinctions are based mainly on the di.stribution of setal types in the thorax. In 

 the following key this is shown by a thoracic formula where: 



C = capillary seta P = peristome 



O = without seta H = hooded hook 

 Notosetae are shown above the line and neurosetae below. The total number of thoracic segments 

 includes the peristome. 



1 Thorax with 9 setigerous .segments including the setigerous 



peristome. [First 5-7 segments with capillary setae and 

 remainder with hooks in female but notosetae of setigers 8 

 and 9 as stout genital .setae in male (Capitella). No branchiae 



or parapodial projections on abdominal segments] 2 



1' Thorax with 10 or more setigerous segments following the 



achaetous peristome 2 



2 Ten thoracic setigers following peristome. 



(Formula: P + — r rr-- = 11. Abdominal neuronodia with 



4C + 6H 

 short rows of hooks. No gills (Mcdioinasti/.^)] M. califoniierisis 



2' Eleven thoracic setigers following peristome 3 



2" Twelve thoracic setigers following peristome. 



[Formula: P + -^ = 13 (Lt ioclindcs)] L. palluhor 



2'" Thirteen to fifteen thoracic setigers following peristome 7 



3 Last six thoracic setigers with hooded hooks. 



[Formula: P + tt; r-r = 12. Saclike gills above neuro- 



5C + ()1I 



podia of terminal campanulate abdominal segments (H( tcro- 



iH(i.^tHs) I H. filif(>r»ii.^ 



3' Thorax without hooks or only in last one or two .setigers 



( A'('/(*//»(.s-/».s) 4 



4 All 1 1 thoracic setigers with capillaries in both rami; 



formula: P + —- — = 12. Abdominal neuropodia with super- 

 ior branchial lobes 5 



4' First thoracic setiger without neurosetae; last setiger some- 

 times with hooks. No bi'anchiae 6 



<)8 



