(13) 



Phoro-ais. Caldwell's (ca) viev; that tney are not mesoderm 

 cells is undoubtedly correct. My o bservatioiiS agree v/i th 

 those o-f' Ikeaa (9) for I find the "plasmic cortnacles" much 

 smaller than any of the cells of the blastula a^.a do not fina 

 tnem with nuclei. In Phcronis architecta they do not appear 

 until the late blastula stat'C (ng.l4) at which tirue the in- 

 ner ends of the cells are aensely i^ranular. It seems very 

 probable that the corpuscles are pushed cut from the densely 

 granular part of the cell aiid that as Calawell and Ikeda have 

 held they are an extra supplv' o i' iiouri shment , 



The blastulae, ^astrulae and youii^ larvae o ■!" Phoronis ar- 

 chitecta are quite similar ijx appearance to those of Phoronis 

 d'Helgoland whicii Lont^champs (12) has figured. Tiie develop- 

 ment is more ret,ular than that of most other species vr.ich; i o 

 probably due to the fact that the eggs and embryos are not har- 

 bored in the tentacular c-u.vn, 

 Gastrulatioi i ana "Purth.er Cha nges in _t 1 \e T'orm of the Larva. 



In the blastula, v/hich has just be^un to inva^jinate, the 

 invagination is eccentric thus i^ivin^^ the first indication of 

 the bilateral symmetry of the larva. This is further empha- 

 sized in the young gastnila of Phoronis architecta by a thick- 

 ening 0*^ the ectoderm cells, v;l;ich becomes the gan^^lion of the 

 Actinot rocha. The cgIus composing th.is thickcnin,- of the cc- 



