30 NILS ODHNER, NORTHERN AND ARCTIC INVERTEBRATES. V. PROSÜBRANCHIA. 1 DIOTOCARDIA. 



fms, shingles, 1 sli., 1. 20.3 (v. Yhlen). — NW. off Siggen, Bergen, 100 fms, 3 shs, 

 max. 1. 47 (1875). — NNW. off Bergen, 90—150 fms, fish bank, many shs, max. 1. 

 53 (Olsson). D:o, 90 — 170 fms, 3 shs, max. 1. 42.5 (Uddström). — Bergen, 4 shs, max. 1. 

 28.5 (M, Sars). — Trondhjem, 5 shs, max. 1. 47 (Sundevall). — Norvay, without de- 

 finite locality, many shs, max. 1. 52 (Rasch), Fig. 24. 



Shetland: Baltasound, on stones, tide mark, 2 sps, max. 1. 23 (Hammar- 

 sten 1909). 



Yarieties: 



Shell with coarse ribs, type, Fig. 26; with fine but sharp ribs, var. depressa 

 Pennant 1777, Fig. 24; depressed; fine ribs; inside dark bluish, var. coem^ea Linne 

 1767 (in Jeffreys 1865), Fig. 25. 



Limits of formal variation: 



54—58 

 46-50 

 20-28 

 17-26.8 



General Distribution: 



Norway to Lofoten, I. 39 (G. O. Sars 1878); to Vanö, 70° N. (Schneider 1895). 

 Nordlanden (Krause 1887; Loven 1846). — West coast (Friele 1874; Lilljeborg 1851). 

 — Christianiafjord (Asbjörnsen 1854). — Bohuslän (Loven 1846; Malm 1855). — 

 Denmark, Bulbjerg, dead sh. (Mörch 1871); west coast of Jutland (Christensen 1907). — 

 Faroes 1, 60 (Mörch 1868). — British Isles (Jeffreys 1865). — Dogger Bank (Har- 

 greaves 1910). — Holland and Belgium, rare (Maitland 1897). — France, very com- 

 mon (Locard 1892). — Portugal, abundant (Nobre 1905). — Mediterranean (Carus 

 1889). — Cape Verde Isles (Jeffreys 1865). — Azores (Dautzenberg 1889). — Tide 

 mark, in deeper water dead shells. 



Helcion pellucidum (Linne 1758). 



PI. 1 figs. 27—32. 

 Habitat: 



West coast of Sweden: KuUen (Lilljeborg 1852"), many shs, max. 1. 16; 

 br. 12; h. 4.8 (Mus. U.); Skane, off Hallands Väderö, NW. to N. of Torekov, 8 fms. 



1. j 14—18 22—26 30—34 38—42 46—50 



Scandinavia; br. ' 10—15 16.8—23 24—30 30—38.4 37—45 



75 sps li. I 3.5— 8 5.5— 10..S (7)'9-16 13—19 15—25 



measured apex i 4.5—7 7.2—10.2 10.8—14.4113.8—18 10.4—21.6 



^ Exceptional, 1 sp. from Väderöarua. 



