676 R, C. PUNNETT. 
nk. = keel of nuchal skeleton. per. =vight proboscis end vesicle. 
nl. = layer of nerve fibrils (Punkt-substanz). vy. = either (1) racemose organ or (2) dorsal root. 
0. = oesophagus. rde. = right diverticulum of dorsal proboscis coelom. 
oep. = oesophageal epithelium. s. = stomochord. 
07 = oesophageal nerve. Se. : : 3 
abate : : NS cavity of lateral diverticulum of stomochord. 
p. = proboscis coelomic cavity. sid. 
pb. =parabranchial ridge. sk.1. = nuchal skeleton. 
pbg. = post-branchial groove, skg. = branchial skeleton. 
per. = pericardium. th, = tongue bar. 
ph. = perihaemal space. v. = vermiform process of stomochord. 
pg. = pygochord. em. = ventral nerve. 
pig. = pigment. vpe. = ventral proboscis coelom. 
pnp. = posterior neuropore. wv. = ventral recurrent vessel of proboscis, 
pp. = proboscis pore. vs. = ventral septum. 
pph. = peripharyngeal space. vv. = ventral vessel. 
pvl. = left proboscis end vesicle. 
PLATE XXXVII. 
Fig. 1. Ptychodera asymmetrica, x 3. 
Fic. 2. Pt. viridis, ventral view. Slightly enlarged. 
Fic. 3. Balanoglossus carnosus. Slightly reduced. 
Fig. 4. Pt. flava, var. gracilis. x 2. 
Fic. 5. Pt. flava (var. maldivensis?). Regenerating. x 1. 
Fic. 6. Pé. viridis, dorsal view. Slightly enlarged. 
Fic. 7. Pt. viridis, lateral view. Slightly enlarged. 
Fic. 8. Pt. flava (var. maldivensis?). Regenerating. x 1. 
Fic, 9. Pt. asymmetrica. A large specimen. Slightly enlarged. 
PLATE XXXVIII. 
Fic. 10. Ptychodera flava, var. gracilis, Preserved specimen from Hulule, x 3. 
Fie. 11. Pt. flava, var. parva. From preserved specimen, x 3. 
Fic. 12. Pt. flava, var. cooperi. From preserved specimen. A small portion of the caudal end 
probably missing. x 5. 
Fic. 13. Spengelia porosa. A small portion of the hepatic region. x 4. 
Fic. 14. Willeyia biswleata. Anterior end seen from dorsal surface. ~ 3. 
Fic. 15. Balanoglossus parvulus. Section through the collar cord. A small clot of mucous substance 
Fic. 
is seen in the lumen. x 85. 
16. 
off the collar cord. 
Pt. flava, var. parea. 
x 20. 
Section through anterior collar region with the Ist dorsal root coming 
