430 
species exposed to tlie waves would float for a miich lesser time 
than those in a vessel as in my experiments. 
II. III. To support the view that great masses of shells are 
washed out and washed down from precipitous coasts and steep 
slopes the following observations may he set forth: 
a) It seems quite normal that shallow water shells are 
secured at considerable depths when dredgings are carried out on 
steep slopes or at the base of these. 
b) Among the shallow water shells hawled up from considerable 
depths there sometimes happens to be living specimens. Friele re- 
cords for instance that he in the Østerfjord in Norway, where the 
coasts are exceedingly precipitous, has taken living specimens 
of Mytilus edulis and Littorina rudis at a depth of 350 fms. Both 
these species belong, as is well-known, to the littoral zone, and reach 
hardly depths of more than 5 to 25 fms. There is no doubt that 
these, as Friele remarks „ere løsnede fra Littoralbæltet og ustandset 
rullede ned i Afgrunden^. ' 
c) Among the marine shallow-water shells that have been 
dredged at great depths a few Land- & Freshwater molluscs may 
sometimes occur. Thus Jeffreys recordsthat there in the great 
Shell-heap which „Porcupine“ came across at the above named 
St. 16 (994 fms.), west of Portugal, also occurred a fragment of 
Melampus inyosotis, which lives on the sea shore. Jeffreys writes 
about this: „It seemed probable also that the deposit was partly 
caused by tidal action, because a fragment of Melampus myosotis 
(a littoral pulmonibranch) was mixed with deep water and oceanic 
Pectinibranchiates and Lamellibranchiates“. Jeffreys records like- 
wise that a freshwater form, Bythinia rubens Ménke, was found 
H. Friele: „Oversigt over de i Bergens Omegn forekommende skal- 
dækto Mollusker “. Forhandlinger i Videnskabs Selskabet i Christiania 
Aar 1873. p. 299. 
C. W. Thomson; The depths of the sea. London 1873. p. 183—184. 
Jeffreys: Keport from „Lightning“ and „Porcupine“ Exp. Proc. 
Zool. Soc. 1884. p. 129. 
