280 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 j 



Proboscis. Proboscis sheath less than % as long as body. Basis of 

 central stylet very long and slender, about 2 to 3 times as long as the I 

 slender, curved stylet ; each of the 2 lateral pouches usually contains 5-7 

 cui-ved accessory stylets (Fig. 40). 



Habitat. Abundant in many localities beneath stones and among 

 mussels and other growths on rocks and piers between tidemarks and 

 below. Often in muddy situations with decomposing organic matter and 

 sometimes in brackish water. Sometimes nearly a dozen may be associated 

 in a single tangled mass. 



Distribution. Northern coasts of Europe to Mediterranean and Ma- 

 deira and from the Aleutian Islands and coast of Alaska to Ensenada, 

 Mexico. Also reported from Chile. 



Reproduction. Sexual maturity occurs as early as March on the coast 

 of southern California and in early summer farther north. The very 

 numerous gonads surround the intestinal canal; a dozen or more may 

 occur in a single transverse section of body; gonaducts open ventrally 

 or dorsally, according to position of gonads. Several hundred ova may be 

 included in a single ovulation. Development is of the direct type and 

 occurs readily after artificial fertilization. The newly hatched young 

 worms are abundant among mussels and other growths on rocks and piers 

 during April and May in southern California. 



51. Emplectonema purpuratum Coe, 1905 



E. purpuratum Coe, 1905a. 



Habitat and Distribution. At present known from only 2 specimens 

 collected by the U.S.F.C. Steamer Albatross at Adakh Island (Aleutian 

 group ) , Alaska. 



Genus NEMERTOPSIS Burger 



Only a single species of this genus is at present known from the 

 Pacific coast. 



52. Nemertopsis gracilis Coe, 1904 

 (Plate 24, fig. la) 



N. gracilis Coe, 1905, 1905a. 



Habitat. Often abundant among corallines, mussels, and other 

 growths on rocks and piers exposed to the full force of the surf; usually 

 near low-water mark and below. 



