NO. 9 MARINE INVERTEBRATES, ALASKA — MacGINITIE I43 



taken. A few were washed ashore, i came from Elson Lagoon (7 

 feet of water), 13 were taken through the ice at 162 feet, and the 

 remainder came from hauls from no to 741 feet. 



Fifteen specimens of Trichobranchus glacialis Malmgren were 

 taken at depths of 162 to 295 feet. 



Seven species of sabelHds, two new to the western Arctic and the 

 other five new to Arctic Alaska, were taken : Chone duneri Malmgren 

 (21 specimens) from 80 to 295 feet; the variable-colored C. infundi- 

 bidiformis Kroyer (32 specimens) from 118 to 295 feet; Euchone 

 analis (Kroyer) (3 specimens) from 216, 217, and 741 feet ; Myxicola 

 infundibidum (Montagu) (2 specimens) from 151 and 213 feet; 

 Potamilla neglecfa (Sars) (24 specimens) from 130 to 741 feet; 

 P. reniformis (Leuckart) (15 specimens) from 130 and 328 feet; 

 Sabella crassicornis Sars (15 specimens) from 217 to 741 feet. 



The tubes of this group are unusually variable : Myxicola in- 

 fundibidum lives in a tube of transparent, viscous mucus, so thick that 

 it appears more like a mass of mucus than a tube. Potamilla reni- 

 formis lives in a horny tube with adherent sand, and the free end 

 curls like a scroll when the worm draws inside. The Point Barrow 

 specimens were in holes in rocks. P. neglecta lives in transparent 

 horny tubes that are somewhat sand-encrusted. Sabella crassicornis 

 lives in a cylindrical tube, the free end of which is grayish and flexible, 

 and the embedded end transparent, rigid, horny, and covered with 

 sand grains. 



Potamilla neglecta retains its eggs within the tube until the larvae 

 hatch. They are laid in a single layer on the wall of the tube about 

 one-third of the way down ; they are held in place by a thin, trans- 

 parent membrane between the eggs and the worm. 



Two species of serpulids, both new to Arctic Alaska and the west- 

 ern Arctic, were found. The sinistrally coiled tubes of Spirorbis 

 granulatus (Linnaeus) were found on bryozoans, hydroids, and 

 stones. Eggs were being incubated in the operculums on August 17, 

 1949 (741 feet) and on February 18, 1950 (162 feet). The dextrally 

 coiled tubes of Spirorbis spirillum (Linnaeus) were found on the 

 bryozoans Porella compressa (125 feet) and Dendrobeania murrayana 

 (175 feet), and Bidenkapia spitzbergensis and Dendrobeania mur- 

 rayana (184 feet), on bryozoans growing on the crab Hyas coarctatus 

 alutaceus (175 feet), and on the spines of the tunicate Boltenia echinata 

 (217 feet). Eggs were being incubated within the tube on Septem- 

 ber 29, 1948 (125 feet) and on August 30, 1949 (184 feet). 



