BY JAS. P. HILL. 
41 
ol. Opening of lumen of notochord into the throat, p. Proboscis pore. 
pbc. Proboscis cavity, pc. Proboscis canal, phs. Perihaemal spaces, pps. 
Peripharyngeal space. rf. Radial fibres passing between the outer and 
fore walls of anterior rim of collar, rt. "Roots." sen. Subepidermic 
capillary net of collar, slv. Median longitudinal vessel of the subepidermic 
capillary net in the posterior ventral part of the collar, sn. " Synaptikel." 
sp. Splanchnic epithelium of proboscis ccelom. spr. Septal prong of gill 
skeleton, thh. Throat or mouth cavity, tpr. Tongue prongs of gill skeleton. 
tre. Trunk ccelom. vcs. Ventral collar septum. vgb. Ventral gonad 
branches, vgs. Septal vessel, vn. Ventral nerve stem. vp. Ventral pro- 
boscis pockets, rps. Ventral septum of proboscis, vv. Ventral vessel of 
trunk, vie. Ventral wall of heart bladder. 
Ptychodera atjstraliensis. 
Plate i. 
1. — Enlarged dorsal view of a small preserved specimen. 
2. — Dorsal view of a portion of the abdominal region showing the two 
epidermal stripes. ( x 3. ) 
3. — Central part of a transverse section of the proboscis passing 
through the anterior free projection of the infolded ventral 
wall of the heart bladder. Zeiss A., oc. 1., cam. Inc. 
4. — Transverse section slightly posterior to fig. 3, but from another 
series especially showing the infolding of the ventral heart 
bladder wall. Zeiss A., oc. 1., cam. luc. 
Plate ii. 
5. — Transverse section passing through about the middle region of 
the proboscis organs. Zeiss A., oc. 1., cam. luc. 
6. — Portion of glomerulus in trausverse section. Zeiss D., oc. 1., 
cam. luc. 
7. — Transverse section of the splanchnic epithelium on the notochord. 
Zeiss D., oc. 1., cam. luc. 
Plate in. 
Fig. 8. — Transverse section through the beginning of the proboscis neck. 
Zeiss A., oc. 1., cam. luc. 
Fig. 9. — Transverse section of proboscis neck posterior to fig. 8 and pass- 
ing through the ventral blind sac of the notochord. Zeiss A., 
oc. 1., cam. luc. 
Fig. 10. — Transverse section of proboscis neck passing through the pro- 
boscis canals and the connecting vessel between the efferent 
proboscis vessels. Zeiss A., oc. 2., cam. luc. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
