98 



developed in pairs, one tentacle on each side of tbose of tlie 

 Fig. 24. first set, as in -^j^, 05. 



fig. 25, whicli 

 is one cluster 

 of tentacles at 

 the time when 

 the fourth set 

 of tentacles is 

 developed. The lurmula 

 of fig. 24 is : 



2T^, 2T\, 

 or, 2 t = 8 Ti r= 8 ^ 

 That of fig. 25 is : 



Younof 



a superciliaris. 



T.TgT.T^TiT^TgT, 



for each chymiferous tube, 



2 Ti 2 Ti 1 



2 T2 2 T2 



2 Tg 2 Tg 



2 T. 2 T, 



or, St=:8Ti + 8T2 + 8T3 + 8T4.= 32L 



In Nemopsis BacTiei Ag. the tentacles are developed in pairs, on 

 each side of the chymiferous tube, as in Bougainvillia ; the only dif- 

 ference being that, in Nemopsis, the first set of ten- Fir;. 2r,. 

 tacles consists of four, instead of two tentacles, as in 

 the former genus. In fig. 26 we have a young Nemop- 

 sis with the tentacles of the first set ; its formula is : 

 4 Tj, 4 T^. In fig, 27 there are two additional sets 

 formed, and the formula is : 



"1 ouuj^' j\ cwopsis 

 , Bachei. 



Tg T2 Ti Ti Ti Tj, T2 Tg, for each chymiferous tube ; 



or, 2 1 = 16 Tj -f 8 Tg + 8 Tg = 32 < ; 



