512 



Cresswell Shearer 



22. Scliiiltz, E. , Aus dem Gebiete der Regeneration. 3. 4. in: Zeit. Wiss. Z. 



75. Bd. 1903 pag. 391—420, 473—494 T. 27, 28, 33. 



23. , Über Mesodermbildung bei Phoronis. in: Trav. Soc. Natural. Péters- 



bourg Vol. 28 1897 Prot. pag. 47—50. 



24. Selys Long-champs, M. de, Recherches sur le dcveloppement des PAoro?m. 



in: Arch. Biol. Tome 18 1902 pag. 495—597 T. 22-24. 



25. , Développement postembryonnaire et affinités des Phoronis. in: Mèra. 



CI. Sc. Acad. Sc. Belg. Tome 1 1904 150 pgg. 7 Taf. 

 20. Wageiier, R., Über den Bau der Adinotrocha hrauohiatu. in: Arch. Anat. 

 Phys. 1847 pag. 202—206 T. 9. 



Explanation of Plates 31 — 33. 



Le ttering. 



an anus. 



hl blastopore. 



col.c collar cavity. 



corp.m blüod corpuscle mass. 



eet ectoderm. 



Int intestine. 



m mouth. 



ones mesoderm. 



m.f mesenchymatous fibres. 



iiep.c canal of uephridia. 



nep.p nephridial or anal pit. 



oes Oesophagus. 



per peritoneal lining of trank cavity. 



pl.c plastic corpuscles. 



pre.c preoral cavity. 



pre.l preoral lobe. 



ree rectum. 



seg.G segmentation cavity. 



sol solenocytes or excretory cells of 



the nephridia. 

 stm stomacb. 

 i'.t".i"' first, second and third larvai 



tentacles. 

 tr trunk. 



tr.c trunk or main body cavity. 

 tr.c.d dorsal portion of the trunk coelom. 

 tr.c.v ventral or lateral portions of the 



trunk coelom. 

 v.gr ventral groove or primitive streak. 

 v.mes ventral mesentery. 



All the figures have been drawa under an oil immersion, giving an 

 approximate magnification of 700 X- They are roughly proportional to one 

 another. 



Piatesi. 



Fig. 



Fiff- 



1—4. Phoronis hippocrepia, Sections of blastulae. 



5 — 7. Phoronis hippocrepia, Sections of gastrulae. In fig. 5, the section 



iß taken through a region slightly posterior to the poiut where the 



blastopore lips are meeting. 

 Fig. 8 — 10. Pk. psammophUa, Young larva collected in the Tow Faro Messina. 

 Fig. 1 1 and 12. Ph. psammophila, Nephridium early stage. The solenocytes are 



Seen arising from the sides and ends of the nephridial canal. 



Pk. psammophila, Dorsal view showing the trunk cavity and the 



nephridia. The connection of the two lateral portions of the trunk 



coelom dorsal to the rectum is shown. 



Ph. branchiata , Median section showing the ventral portions of tbe 



trnnk coelom. 

 Fig. 15 and 16. Ph. hippocrepia, Nephridium early stage. 



Fig. 13. 



Fig. 14. 



