310 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL.2 



Family Nectonemertidae 

 Genus NEGTONEMERTES Verrill 



97. Nectonemertes pelagica Cravens and Heath, 1906 



N. pelagica Coe, 1926, 1931. 



Habitat and Distribution. Bathypelagic ; swims or floats sluggishly in 

 a cold-water layer at depths of 50-500 m or more off the coast of Cali- 

 fornia and northward. Also (probably the same species) at depths of 

 nearly 4,000 m off the west coast of South America. 



Order BDELLONEMERTEA 

 Family MalacobdelHdae 



Genus MALAGOBDELLA Blainville 



98. Malacobdella grossa (O. F. Mliller), 1776 



M. grossa Burger, 1895; Gering, 1911; Guberlet, 1925; M. obesa, M. 

 mercenaria, Verrill, 1892. 



Habitat. This widely distributed species occurs on the Pacific coast 

 as a commensal in the mantle cavity of Soliqiia patula, Macotna secta, 

 and presumably other bivalves. On the Atlantic coast it is found in 

 Venus mercenaria and Mya arenaria and occasionally in Ostrea virginica; 

 on the coasts of Europe in Mya truncata, M. arenaria, Cardium aculea- 

 tum, Isocardia cor, Venus exoleta, V. mercenaria, Pholas crispata, 

 Cyprina islandica, and Mactra stultorinn ; and in Japan the same or a 

 closely related species occurs in Mactra sachalinensis. The proportion of 

 infestations in some localities may be as high as 75 to 90 per cent in 

 certain years (Guberlet, 1925). 



Distribution. Northern coasts of Europe, Mediterranean ; Nova 

 Scotia to Chesapeake Bay; Puget Sound to California; (Japan?). 



