Section IV, 1918 



[53] 



Trans. R.S.C. 



The Vertical Distribution of Certain Intertidal Animals. 

 By A. G. Huntsman, B.A., F.R.S.C. 



(Read May Meeting, 1918.) 



In 1917 we determined the vertical distribution of several mm 

 mon mtertidal species at two widely separated points on ourAlandc" 

 coast, where very different physical conditions obtain. Tt St Ïn 

 ofT% ?.' "'"''"' °" ''^ '*• ^^«'^ "-^' - estuary of the Bay 

 to " /;. T " '".'";""^ '^'"' ^"^P^^^"^^ °f --e than twenty-five 



hi; at Vhe' T^ '-"'^ '""^"^^ P^°^"^^^ -- ^he water so thorough^ 

 that at the surface it never is of low salinity nor does it ever atS n 

 a very high temperature even at the end of summer Dr W BeH 

 Dawson very kindly established a low-^-ater datum at th^ Bilgt 

 Station wharf and installed a tide-gauge. We are indebted /nT 

 also for the calculation from the tidal dat nhl ^'f j^^^.^^^^d to him 

 r^f 1017 f ..u ^^^' Obtained during the season 



of 1917, of the percentage of the total time that various levels above 

 the low water datum were covered and uncovered by the wlter The 



tota, number of hours cot::lr„cltVb:^Tdet;rmre"d Td^thil 

 value subsequently reduced to the percentage of the tot"! tt'e 



Biological Station, St. Andrews. N.B. 



Periods, June 15 to July 14- 

 Oct. 1 to Oct. 29, 1017. 



Height above low-water datu m 

 Months 



Total number of hours covered! 



or uncovered 79 :20 



Mean monthly total in hours.. 88^ 

 Mean monthly percentage of 



total time | 12 42 



From these figures we have constructed a diagram (see fip-nrP U 

 which shows in a graphic manner the percentage of th.. f I !' ^' 



r=ii:^:rsTi^rei~^^ - 



wMth has been ta.en to repres"entThe el'^ tt«" ^^.^ 



