124 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Fig. 6. Trochophore larva, Dec. 30th, 1898, and Feb. 
ord, 1899. 
Figs. 7 and 8. Post-larval stages of Polycheta, of which 
Fig. 
Fig. 
Fig. 
| Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
a 
many were taken during April, 1899. 
PuatTE VII. 
Holothurian larva, Jan. 24th, 1899. 
Echinoderm Blastosphere, at close of segmenta- 
tion, Dec. 17th, 1898. 
Gastrula stage of fig. 2, in optical section. a.c., 
Ameoeboid cells budded from the invagination. 
Asterid Gastrula, Jan. 24th, 1899. 
Later stage of fig. 4, showing the archenteron, ar. 
Still later stage, from ventral surface. ar., 
archenteron, from which the enteroccelic vesi- 
cles, v.p.d., are derived. The water vascular 
rosette is derived, according to Metschnikoff, 
from the left vesicle, that on right of figure. 
Tornaria larva of Balanoglossus, June 5th, 1899. 
Bipinnaria larva, Feb. 23rd, 1899, from dorsal 
surface. @., Oesophagus; a., Anus; hy., Hy- 
dropore; v.p.d., anterior enteroccelic vesicles. 
Figs. 9 and 10. Tornaria larve of Balanoglossus, June 
23rd, 1899. p.p., Proboscis pore; p.c., Proboscis 
cavity. Figure 10 is most probably identical 
with the Tornaria figured by Mr. G. C. Bourne 
(Journ. Mar. Biol. Assoc., vol. I., p. 63, Pl. 
VEILS tie.A3), | 
