WIGLEY and STINTON: REMAINS FROM MARINE SEDIMENTS 



Table 11. — Bathymetric distributions of 44 gastropods 

 and the number of stations at which each occurred. 



Water depth 



Number 



1 Only one species appeared to be represented— possibly a Thais. 



OS, L. levicula, Mitrella lunata, Neptunea 

 decemcostata, and Odostomia sp. 



Species taken only in deep water — those re- 

 stricted to depths greater than 200 m — were: 

 Alvania janmayeni, Anachis costulata, Eulimella 

 smithi, Taranis cirrata, sindi Turrtellopsis acic- 

 ula. All these species were taken at only one 

 station, except Anachis costulata, which oc- 

 curred at two stations. 



Shells of individual species of gastropods gen- 

 erally occurred at low or moderately low densi- 

 ties. Only three were found in high or moder- 



Figure 14. — Bathymetric range and mean depth of 

 occurrence of the more common gastropod species. 

 (Observed values are listed in Table 11). 



ately high concentrations: Alvania carinata 

 (630/m'-), Cylichna gouldi (530/m-), and Nas- 

 sarius trivittatus (130/m-). The density of 

 other gastropods (41 species) was 60/m- or 

 less. 



Species-Sediment Relations 



The majority of gastropod species occurred 

 in sand and silty sand. None was in coarse sand 

 or gravel-sand substrates, and none appeared to 

 be restricted to silt. Widely distributed species 

 generally occurred in a variety of sediment 

 types ranging from medium sand to silt. A few 

 species were associated with specific sediment 

 types. Gastropods found chiefly in sand sub- 

 strates were: Colus pygmaeus, Crepiduki for- 

 nicata, Cylichna alba, Lunatia levicula, Nassar- 

 ius trivittatus, and Odostomia canaliculata. The 

 only species found principally in fine-grained 

 sediments was Epitonium dallianum; it was 

 mainly in silty sand. 



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