EMBRYOLOGICAL MONOGRAPHS, 
IGP AMIN ID, \Y TIE 
Development of the SteHonopHora continued. Figures from ALexanper AGassiz, J. WALTER | 
Fewxkes, and Evias Merrscunrkorr. . 
A. a Anterior. P. prey.  Pneumatoeyst. 
ax. Axis. pu ph. Pneumatophore. 
C. C.P.Z. Chamber in the larva, which ulti- pr. hy ph. Primitive hydrophyllium. 
mately becomes a canal in the PY: Polyp. 
primitive hydrophyllium. py.s. — Polyp stem. 
el. Cell. pyt. Polypite. 
cn. Canal. De Radial tube. 
E. eb. Epiblast. S. sac. Sacculus. 
ev'. Infolding or thickening of the epi- ser. hy ph. Serrated hydrophyllium. 
blast to form the future pneuma- T. ta. Tentacle. 
tophore. t. vs. Terminal vesicle. 
em. ta. Embryonic tentacles, with embryonic Vi Ventral. 
knobs. vt. Vitellus. 
F. fil. hy cy. Filament of the hydroeyst. a. Ampulla-like enlargement of the 
G. ga. Stomach. canal of the first formed hydro- 
H. hb. Hypoblast. phyllium. 
hy cy. |Hydrocyst. B. Canal connecting this ampulla with 
Temas Tnvolucrum. that of the axis. 
L. 1. vs. Lateral vesicle. ays Central tube in the serrated hydro- 
MM. ms b. Middle layer (between epiblast and phyllium. 
hypoblast), which forms the gela- & Portion of a chamber in the primi- 
tinous body of the hydrophyllium tive larva, which remains at the 
(mesoblast 2). proximal end of the canal passing 
N. nex. Nectocalyx. into the prinitive hydrophyllium. 
nex!. Undeveloped nectocalyxes. é. Enlargement of the cavity in the 
nl. Nucleus. tentacular knob. 
nt cy. Nematocyst. r. Point of internal attachment of the 
0. or. Mouth. coiled part of the tentacular knob 
P. p. Posterior. to the walls of the body which 
pap. Papilla (2). envelops it, and forms the outer 
pig. Pigment. walls of the knob. 
1-25. Development of Agalma. 
1-11. From the ovum to the ‘‘ primitive larva.” 12-20. From the primitive larva to the ‘* dthorybia larva.” 
21, 22. 
From the ‘‘ Athorybia larva” to the young resembling the adult. 
y y 5 5 
1, 2. Agalma Sarsii. From Metschnikoff, op. ctt., Pl. VIII. figs. 1, 2. 
1. Youngest larva, in which the epiblast (¢.) forms a polar cap. The vitellus (vf.) is penetrated by a proto- 
plasmic network, which divides it into a spongy mass of glass-clear cells, as in Cfenophora and other 
Stphonophora, The external surface is ciliated. 
2. An older larva, which has become elongated and more pyriform. The deeper layer (2.), which is called 
endoderm (hypoblast) by Metschnikoff, may be the beginnings of the chamber C. P. Z. The epiblast and 
hypoblast, probably both together, form the layer e }. 
