MATERIALS FOR A MONOGRAPH OF THE ASCONS. 353 
Fie. 57.—Section of the oscular rim; on the extreme right the first collar- 
cell is drawn in outline; on the inner (lower) side four cells of the dermal 
epithelium come into the section, but on the outer side none are cut through, 
since the section passes between them. m.sp. Menaxon spicule with two 
formative cells. sc/. Scleroblast on the ray of a triradiate cut across. ea.c. 
Txeretory cell. 
Fre. 58.—Young triradiate from a section showing the unpaired ray in its 
full length, bearing the basal and apical formative cells (d.fc., a.fc.). The 
two paired rays are cut off close to their origins, but show their basal forma- 
tive cells. 
Fic. 59.—Gastral ray of a quadriradiate, from a section showing the 
granular actinoblast with two nuclei. 
PLATE 19. 
Figs. 60—70.—Gastral rays of quadriradiates, from vertical sec- 
tions of the body-wall of Leucosolenia complicata. 
Fie. 60.—Young quadriradiate showing the unpaired basal ray, broken, 
with the two formative cells (4.fc., a.fc.), and the gastral actinoblast (g.act.), 
with two nuclei. 
Fic. 61.—Young quadriradiate showing two scleroblasts of the triradiate 
system and the gastral actinoblast (y.ac¢.) with two nuclei, which have appa- 
rently originated by very recent division of the original nucleus. 
Fie. 62.—Quadriradiate with the gastral ray (broken in two places) bearing 
the actinoblast with two nuclei, and close to the base, among the collar-cells, 
an excretory cell (ea.c.). 
Fre, 63.—A quadriradiate, showing two formative cells of the basal system, 
and two nuclei on the gastral ray, near the base of which is seen an excretory 
cell (er.c.), apparently connected with the gastral actinoblast by a proto- 
plasmic process. 
Fre. 64.—A gastral ray of a quadriradiate, showing the tip enveloped by 
the actinoblast, and with an excretory cell (er.c.) attached, from which 
granules are being ejected. It was difficult to be quite certain if the actino- 
blast contained one or two nuclei; possibly one has been cut off. 
Fig. 65.—Similar to the last; gastral actinoblast distinctly with two 
nuclei. 
Fies. 66, 67.—Full-grown -gastral rays, each enveloped in an actinoblast 
bearing two nuclei (z.act., z.act.), and carrying two excretory cells (ez.c.). 
Fie. 68.—Portion of.a section through the oscular rim; the first collar-cell 
is seen on the extreme right. g.7. A gastral ray covered partly by the dermal 
epithelium (d.ep.), but not bearing an actinoblast or excretory cell. 
