112 



ART. 4. N. YATSU I 



rn. pr parietal muscle. 



m. vt ventral muscle. 



mg. I marginal lacuna. 



ms mesenchyme. 



ms. ent mesentoblastic cell mass. 



msb mesoblast. 



mt mantle. 



mt.fd mantle fold. 



nph nephridium. 



obl. ex M. obliquus externus. 



obl. int M. obliquus internus. 



obl. md M. obliquus médius. 



occ. mit M. occluor anterior. 



occ. pst M. occlusor posterior. 



ces oesophagus. 



ot otocyst. 



2%l peduncle. 



pd. cv peduncular cavity. 



pli. sn palliai sinus. 



pr. ly peritoneal layer. 



pyrt protegulum. 



pst.dr.lv posterior dorsal lobe of 



liver. 



sg. cv segmentation cavity. 



sh shell. 



sm. am. sn.... small arm sinus. 



sp. I layer of supporting sub- 

 stance. 



st seta. 



stm stomach. 



stmd stomodeal invagination. 



tnt tentacle. 



vc. ly vacuolar layer. 



vit. mb vitelline membrane. 



vs. ly visceral layer of meso- 

 blast. 



vt. gn ventral ganglion. 



vt. Iv ventral lobe of liver. 



vt. mes ventral mesentery. 



vt. mt ventral mantle. 



vt. sh ventral shell. 



yk. ly yolk layer. 



