29, 
EMBRYOLOGICAL MONOGRAPHS. 
PLATE VI. 
Development of the DiscomEsa and SipHonopwora. Figures from ALEXANDER AGassiz, Carb 
Cuun, J. Water Fewkes, Ernst Hacker, Evtas Merscunixorr, ard P. E. Miuurr. 
A, a. Anterior. msb. Mesoblast. 
a.nex, Anterior nectocalyx. N. nex. Nectocalyx. 
ax. Axis. ntcy Nematocyst. 
C.C.P.Z. Chamber or tube in the primitive hy- O. oa. Ovary. 
drophyllium, which is derived from or. Mouth. 
a cavity early formed in the ovum. P. pab. Undigested food in the stomach. 
cil. Cilium. pig. Pigment. 
el. Cell. pnrcy. Pneumatocyst. 
E. eb. Epiblast. puex. Posterior nectocalyx. 
ebl. Infolded portion of the epiblast. pyt.  Polypite. 
em.ta. Embryonic tentacle. R. rv. tb. Radial tube. 
F. fil. hy cy. Filament of the hydrocyst. S. socy. Somatocyst. 
G. ga. Stomach. T. ta. Tentacle. 
gm. Bud. U. ubr. Umbrella. 
go ph. Gonophore. V. vel. Velum. 
H. hob. Hypoblast. vt. Vitellus. 
hv. Large cells (vitelline cells), hypo- a. Float. 
blastic ? B. Partitions which separate the cham- 
hp. Liver? Cluster of “ brown cells.” bers found in the frame-work 
hy ph. Hydrophyllium.. supporting the sail. 
hy cy. Hydrocyst. 7: Partitions which separate the eoncen- 
To ts Interior of bell. tric chambers of the float in the 
L. la. ap. Peduncle of a tentacular appendage disk. 
(tentacular knob). 6. Rim of the disk. 
DM. mb. Membrane. r. Feelers on the under side of the disk. 
mds. gin. Medusa bud. o. Sail. 
1. From a Sketch by A. Agassiz. 
1. Sexual cluster of male and female gonophores of Physalia. mds. gm. Undeveloped medusa bud. goph. Fe- 
oe 
on 
rs 
male gonophore 2, male g. 
From A. Agassiz, Exploration of the Surface Fauna of the Gulf Stream. Mem. Mus. Comp. Zodl. 
Vols VilLl.5) Nos 2)ePlaViloahivstle 2 os 
Young Velel/a in profile. hp. Liver? 6. Rim of the disk. X. Prehensile tentacle (hydrocyst?). o. Sail. 
A large feeding polyp (polypite) hangs down from the middle of the disk on the under side. 
. Young of the same, from below (oral view). In the centre is seen the mouth (or). @. Border of the disk. 
\. Prehensile ‘*tentacles” ? These bodies (X), like the hydrocysts of Physophora, are prehensile. 
. The same, a little older, in which the ramifications of the liver extend to the disk margin or horizontal mantle. 
pyt. Central feeding polyp or polypite. A. Prehensile tentacles (hydrocysts). 
5-7. Rataria. From Sketches by Fewkes. 
. Section through Rataria (young Porpita or Velella ?), found with Veledla spirans. The section passes verti- 
cally through sail, disk border, and retracted polypite. The sail is seen to be composed of a superficial 
