93 



ous tubes as that at -which they are placed one from the other. In the 

 youngest Tiarojjsis -which I have found, fig. 10, there were abeady 

 Fig. 10. twenty-four tentacles, four long tentacles in the 



prolongation of the chymiferous tubes, four 

 slightly shorter in the middle of the space be- 

 tween the eyes, and two pairs of small tentacles, 

 one pair for each eye. So that we should have 

 for the formula of the tentacles of fig. 10 : 

 Ti, ^3, e, fg, <2» ^35 ^» h' Tj ; e being the 

 compound eye. The third set, which would have 

 Yomg'S"7"Ta"- f^^Jen on the spot occupied by e, consists of a 

 mata. pair of tentacles, instead of a single one only, 



as in the former cases. 



Fig. 11 is a diagram of the arrangement Fig. il. 



of the tentacles, between two chymiferous 

 tubes, in the stage of growth of fig. 10. 

 When we come to the next stage, represented 

 in fig. 12, the order of succession is not in- 



FiG. 12. terfered with by the eyes, 



and we have for the for- 

 mula of the arrangement of 

 the tentacles : 



-Lx5 '45 '3? ^) '3) '5? *2' ^51 

 *3» ^' ^3' ^4' -'-I* 



The fourth and fifth sets 

 consist only of eight tenta- 

 cles each, and not of six- 

 teen, as the third set. When 

 we come to the next set, 

 the sixth, we find that it 

 has sixteen tentacles, and 

 that two pairs of tentacles 

 Tmrops/s, having forty tentacles. ^re formed, one for each 



eye, as is shown in the diagram, fig. 13, and so on; every set 

 which would have come in the space ^^^ ^^ 



occupied by an eye being always formed 

 in pairs, as was the case with the third 

 and the sixth sets. The formula for 

 this figure (fig. 1 3) would be : 



-""IJ M' 3' ^6' ^» ^6' ^3' '5' '2' 6' 3' ^6' ^' ^6' ^3' 4' 1' 



