(36) 



tacles and a fev; pigment cells are seen on the surface o ^^ the 

 blood corpuscle masses. Usually there are quite a number in 

 tl;e wall o^ the posterior portion of th.e trunk. 



This Actinotrocha is not as active as Species ,B.,atici it aoes 

 not, as a rule, turri up its preoral hoed vmen irritated. Its 

 iiietamorphosis usually takes place quickly, in or 20 minutes be- 

 in^ required f^o r its completion. Actinotrc ciia Species, A., I feel 

 certain, is the Actinotrocha of P. architecta. 

 Speci es, B. (T^if:,.35) ;- 



This Actinotrocha is larger tnan Species, A., and v/hen 

 about ready to inetamorphoso, it ,;as an average length of 1.22 nra 

 and las at least 2G tentacles. (v/il3on(24) figures tne Actino- 

 trocha Species, E., ready to inetaro rphose, vvitn 22 tentacles.) 

 The difference in appearance bef^een this larva and Species, A., 

 is rather striking. Eesiac being some;7hat lon.^er, it is slight- 

 ly narrower in the collar region ana aeciaedly so in the trunk 

 region .hich ,,ives it a rrruch more graceful appearance than that 

 0- Species, A. Tne intestine is ,uite lon^ extendin, through- 

 out the posterior t;vo-thirds o f the t nuik cavity. 



M. Longchamps has kinaly pointed out to me tnat the "adult 

 tentacles appear bilaterally, the mia-vontral line bein,., at 

 first, free of the buds". They do not arise, however, as tnack- 

 enings on the under .i,e of the bases o- the larval tentacles as 



