•90 
ANNIE MATTHEWS. 
Interstitial cells cut off singly from octoderm by mesogloea. 1. Small lobe. 
L. Large lobe. L. J. Junction of supporting lamella of mesentery with 
that of body wall. L x W v Somewhat contracted and therefore wrinkled 
lateral wall of polyp. L. W. Lateral wall of polyp. m v Supporting 
lamella of mesentery growing radially inward from lamella of body 
wall. M. Mouth. M. B. Base of mesentery. M. C. Mucous cell. 
M. F. Mesenteric filament. M. P. Adhesive plug of white mucus, 
attaching base of polyp to substratum. Mes. Mesentery. Mes 3 , Mes s , 
Two lateral mesenteries. Mes. E. Edge of mesentery before ventral 
filament developed. Mg. Mesogloea. Mg±. Mesogloea of mesentery. 
Mg n . Mesogloea flowing between interstitial ectoderm cells at root of 
mesentery. Mg. Tli. Thickened ridge of mesogloea stiffening the line 
of attachment of mesentery to base of polyp. N. Nucleus halved 
by karyokinesis. N«. One of daughter nuclei, formed before first 
segmentation. N 3 . Nucleus. N. T. Nematocyst thread. Ne. Nematocyst. 
Ne v Nematocyst, in mesogloea of mesentery. Ne 4 . Nematocyst, with 
thread stained. 0. P. Oral pole. 0. S. Oral surface, surrounded by 
tentacles. P. Pinnule. P r Earliest developed pinnule on the tentacle. 
P 2 . Latest and youngest pinnule on the tentacle. P. C. Pre-oral 
cavity. P. M. One of eight permanent mesenteries. Pa. Parent 
polyp. PI. Remains of degenerate base of stomodseal invagination. 
R. C. Rounded cells in ectoderm. R. E. Rapidly proliferating and 
therefore temporarily multilayered ectoderm. R. Mes. Recently 
secreted mesogloea. R. Sc. Remains of scleroblast. S. Stomodseum. 
Sc. Scleroblast. Se. Second row of buds. Su. Substratum. St. 
Stolon. Sp. Spicule. Sp v Spicule embedded in mesogloea. Spb> 
Spiculoblast with spicule dissolved out. Spb v Spicule left in scleroblast, 
embedded in mesogloea. S. cell. Cell embedded singly in mesogloea. 
Sub. M. Subsidiary mesentery. S. B. Termination of wall of stomodseum. 
S. C. Segmentation cavity. £?. L. Supporting lamella. S. M. Separating 
membrane. S 4 M v Position occupied by supporting membrane 
in mesogloea of body wall. S. Mg. Mesogloea streaming out from 
endoderm among rounded cells at base of ectoderm. S. 0. S. Sloping 
oral surface. S. 0. Early stage in appearance of strap-like outgrowth 
of ectoderm of stomodseum, over endodermic part of ventral mesenteric 
filament. T. Tentacle. T. B. Swollen base of tentacle. T l B v Very 
young bud of the third row. T. R. Tentacles retracted. T. Sp. 
Tentacular spicules. V. M. Yentral mesentery. V. M. F. One of the 
six ventral mesenteric filaments. V. M. F 1 . Lower limit of ventral 
mesenteric filament. Wr. Wrinkled outline of latest pre-planula stage. 
Y. Yolk globules. Y v Small yolk globules. Y 2 . Large yolk globules. 
Y. D. Yolky detritus. Y. E. Inner half of columnar ectoderm cells, 
.still containing yolk globules. Y. V. Large yolk-containing vacuoles. 
