51 



one of relative position, simply.) The next series of four 

 tentacles in each quadrant, T V to T VIII, brinf^s us 

 to the 32 tentacled staf^e seen in text-figure 6, In this 

 it will bo seen that T V follows T I, T VI follows T II, 

 T VII follows T III, T VIII follows T IV, four numb'-rs in- 

 terveninp- in each case. The next series comprises T IX to 

 T XVI, which follow the same plan in order of appearance, 

 T IX following T I, etc., eight numbers intervening in each 

 case. While this may seem r'lore like a fanciful exercise 

 of the imagination than an actual condition in nature, the 

 truth is that the larger the number of specimens in which 

 one tests the arrangement of the marginal organs by this 

 riile, the more will one be convinced of the remarkable con- 

 stant adherence to it. Given a specimen with, say, 28 ten- 

 tacles, such as that represented in text-figure 7; this is 

 a drawing of a specimen of Olindias , from the Bahamas, a 

 genus which follows t?ie same rule in the order of appear- 

 ance of the tentacles as that which is being described for 

 Gonionema : the sense-organs are not so numerous in Olindia s. 

 In this specimen the most recently arisen tentacle in each 

 quadrant is evidently the one numbered VII, lying just af- 

 ter each perradial tentacle. Then, if the rule which we 



