518 



THE AMERICAN NATURALIST [Vol. LIU 



withstand when used as a fisherman-fish, the problem may 

 he attacked from two standpoints. One might first ascer- 

 tain how much adhesion the sucker would develop or 

 secondly work out the ''pull" necessary to land a turtle 

 or large fish. This has never before been attempted, but 

 it is worth while trying. 



My largest Echeneis had a sucking disk whose longest 

 diameter measured 7.25 X 2.63 inches. Assuming that it 

 was an ellipse in shape let us proceed to get its area. The 

 formula for the area of an ellipse whose longest diameters 

 are a and h is as follow^s: Area =7r X « Xh/A. Substi- 

 tuting and performing tlie oi)erations indicated we get 

 14.98 square inches for the area. This is of course too 

 large, for no allowance has been made for the longitudinal 

 rai)he or for the lamclhe arranged like the slats of a 

 Venetian blind. This cannot be ascertained but we will 

 allow 1.48 square inches for this and thus reduce the avail- 

 nl)le -ucking area to 1 :{..") xiuare iticlio-. It is understood 

 that the fish adlici-es to its host hy rai>iim' its disk through 



this vac'imiu wiM'c perfect t Ik' adlu'^oii luuU\ hr i:5.:) X 14.7 

 l)Ounds or 11)8.45 pounds, or in round minihci s IDS j)()uiids 

 would be the measure of the adhesion of the disk to the 

 host fish, shark or turtle. 



But it is objected that thedi^k eai! IM.t dexelopa iM^feet 

 vacuum, and a> thi> i> ti'iie nm- limires inu>t l)e i-ediiced. 

 Let the reduction he per cent, an.l the .•ulhe.-h.n ^tili 

 99 pounds, or if it he cut hv tliree r(.m-1l!> the adlieslon 

 will still be 49.5 ])()unds. The Intter is pi-obably too low 

 just as the lirst is uiidouhtedl v too hiuii. For one thing 

 there has not been and c;in lu.t he lii-iired out the ad- 

 ditional adhesion dewh.prd 1.x tin. h.-ickuardlv directed 



teeth the hunell.T. which were f'<.l-nierlv thon-ht to do 

 all tin- iioldinu-. A^Mnuin- Hint ilu" liohlin- t'orcr i~ W 

 ponnd^. It uiM be MM.,, th.it ulien 1 p„lh.<l on thi^ ti^h"^ 

 tail uith a pull eMi,„;,le,I at 5i) pounds the liu,it. of its 

 a<lhe^io,i had n.M ,i..arK heeii n.a<-hed. An.] yet at the 

 time it wa> noted that the ii,u>ch'> of the li-h >tuii)ped and 



