Ll ee, ee ee, 
al leet jsc| tel 
. bp. 
« CON. CTC. 
MEM. M. C. Z., IX. No. 3.— ACALEPHS, POLYPS. 29 
PLATE YIII. 
Development of the ACRASPEDA. 
Blastopore. 
Cireular Canal. 
con.t1—con.3 Constrictions which ultimately 
. eb. 
G. 
gt. 
gm. 
ga c. 
. lab. 
_ hb. 
~ man. 
~ mck. 
nl. 
or. ta. 
ope 
py. gi. 
ta. 
tal 
ta,? ta.* 
tb. 
become deep enough to separate 
the intermediate disks as Ephyre 
from the Strobila. 
Epiblast. 
Stomach. 
Bud. 
Portion of the stomach, which forms 
a dish-shaped cavity, as distim- 
guished from that within the oral 
folds. 
Hypoblast. 
Lip of oral tentacle. 
Manubrium. 
Nucleolus. 
Nucleus. 
Ovary. 
Otocyst. 
Otoeyst lobe. 
Style bearing the otocyst. 
Mouth. 
Mouth. 
Oral tentacle. 
Posterior pole of the planula. 
Bud forming on the side of the 
Strobila. 
Tentacle. 
Tentacle of the Seyphostoma. 
Undeveloped tentacle. 
Enlargement of circular canal at the 
junction of the ocular tube. 
Figures from Louis AGassiz. 
tht Tube passing radially from stomach 
to vicinity of sense organ, open- 
ing at the periphery into the en- 
largement (¢b) and centrally into 
radial tube (1b*). 
th.? Tube passing directly from stomach 
to bundle of tentacles. 
tb.3 Tube from stomach in sense octant, 
before division. 
tb.4 Centripetal tube arising from ciren- 
lar canal at the peripheral end, 
ending blindly at the other ex- 
tremity- 3 
the Tube in the lappets of the oto- 
cyst (2). 
tb.6 Angle in tube (f4) which later 
pushes itself into the lappet. 
U. ubr. Umbrella. 
V. vel., vel.1 Velum. 
vt., vt.) Vitellus. 
vt. m.  Vitelline membrane. 
a. Rim of the orifice leading into ova- 
rian cavity. 
B. Base of attachment, also abnormal 
unattached bases. 
B.) Base of a Strobila with large num- 
ber of constrictions. 
ave Chitinous basal support (perisare !) 
Get Gelatinous portion of the umbrella 
between two chymiferous tubes. 
op. Phacellen (sexual filaments). 
¢.! Phacellen, seen through the ova- 
rian opening. 
The figures on this plate were arranged by A. AGAssIz. 
1-9. Aurelia flavidula, from Agassiz, op. cit., Vol. II]. Pl. X. figs. 1, 2; Pl. X*. figs. 16, 17, 19, 20, 22, 23, 24. 
5-8. 
9. Morula. 
1-21. Development of the planula from the ovum. 
1, 2. Ovum (life-size) from ovary. The early conditions are passed through in the ovary and folds of the mouth. 
8. Enlarged view showing the yolk cells in the middle of the ovum. 
4, The vitelline cells occupy the whole vitellus (vt). 
Consecutive stages, with nucleus (77) and nucleolus (xcZ).  v., vt.) Vitellus. vf. m. Vitelline membrane. 
al. nucleus. vt. Vitellus. 
10-20. Acraspedote medusa, Genus? These figures resemble the stages of segmentation of Cyanea. They illus- 
trate the formation of a blastosphere (fig. 20) from an egg where segmentation has just begun, 
