AGASSIZ AND WOODWORTH: VARIATIONS IN EUCOPE. 139 
the tz and ts cycles are very marked (see Figs. 8, 9, 11, 15, and ya 
t, can only be distinguished from the ¢, 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. 14, 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 inerease 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 number 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 
T 109 4 000% 0,9 05 
there are six otoliths, one on each of the tentacles at the base of the 
radial eanals 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, 23 2, 8, 43 2, 3, 33 3, 1, 3, 4; 
