AGASSIZ AXD WOODWOKTH : VARIATIONS IN EUCOPE. 139 



the ^2 fiiid tz cycles are very marked (see Figs. 8, 9, 11, 15, and 17); 

 <i caa only be distinguished from the t^ pair by its position. 



The coalescence at the base of adjoining marginal tentacles to form 

 a double tentacle with two spurs and two lashes is not uncommon. 

 During the summer there were fourteen specimens met with having 

 double tentacles : in all except two cases they were connected with the 

 tentacle riding a sense organ. 



The sensory tentacles usually have only one otolith ; we however 

 observed thirteen cases in which each sense organ contained two (Plate 

 VIII. Figs. 15, 17), and five in which there were three otoliths (Plate 

 VIII. Figs. 11, 16), and one in which there were no otoliths in any of 

 the quadrants. 



An examination of the table on page 137, in which the more interesting 

 of the variations observed have been collected, will show how large a 

 number of specimens show great variation in the number of the sense- 

 bearing tentacles. Among specimens of Eucope with the normal number 

 of quadrants we find the otoliths bearing tentacles vary from eight, the 

 normal number, two in each quadrant, to three on one side and ten on 

 the other. As will be noted, there are only five cases in which the sensory 

 tentacles are greater in number than in the norm, while the number 

 of cases in which they are suppressed is quite large. Their increase 

 does not always accompany an increase in the number of radial canals. 

 Two out of four specimens with five radial canals possessed nine sensory 

 tentacles, another only seven, and one eight. 



There seems to be no correlation between the numljer of marginal 

 tentacles in any sector and the number of sensory tentacles. 



The primary sector with the largest number of tentacles has often 

 only one sensory tentacle, while that with a smaller number has two. 



In a specimen with quadrants of unequal size, and with an unequal 

 number of marginal tentacles, in each of which the formula is 



7 ; 6 ; 1, 5, 5 ; 6, 7, 5 ; 



there are six otoliths, one on each of the tentacles at the base of the 

 radial canals between the first and second and the second and third 

 quadrants, and the others as marked by the comma in the third and 

 fourth quadrants. 



In another specimen with very unequal quadrants there are nine oto- 

 liths, there being three in the largest quadrant, as shown by its formula, 

 the first quadrant being the smallest, the last the largest : 



1, 3,2; 2,8,1; 2,3,3; 3, 1,3,4; 



