ii 
MEM. M. C. Z., IX. No. 3.—ACALEPHS, POLYPS. 35 
PLATE X. 
Development of the CTENOPHORA, continued. Figures from Cart Cuun and J. WALTER FrEwkes. 
A. adr. th. ‘Advadial” chymiferous tube. The mil. Muscles. 
adradial tube passes to the short rows mu.cre. Muscles surrounding the stomach. 
of flappers. It arises from the in- N. n.n.8 Nerves. 
terradial tube. Ne. Nerve centre 
aur3—aur.* Auricles. O. ocy. -Otocyst. 
C. cil. Ciliun. ol. Otolith. 
Gi c Tutt of cilia before closure of otocyst. or. Mouth. 
E. ex'., ex.2 External openings from the funnel, P. per. cn. Radial canal before division. 
probably exeretory. S. sch. Tentacular cover. 
ex. l. th. External lateral tube bounding the s.gw. Gelatinous elevations on the side of 
lower rim of the body lobes (0). the otocyst. 
G. ga. Stomach. sph. Funnel. 
ga. cn. — Bifurcation of the stomach tube. sph. tb. Tubular region of the funnel. 
ga. sch. Magengefassschenkel. T. ta. Tentacle. 
ga. th. Stomach tube. ib.-tb.8 Chymiferous tube extending to the 
gaw. Appendage to the stomach. tentacle. 
HH. hb. Hypoblast. 2 HD Junction of three chymiferous tubes. 
hb.) hb2. Large hypoblast cells. Veery2 Line of the internal wall of the lobe 
hv3,, ht. Beginning of the chymiferous system y.3 at the point where the chymiferous 
of vessels. tubes seem to cross it. 
F 4.ttb: Internal lateral tube. Z. 2z3-2.4 Junction of tubes at base of auricles. 
arth. Internal radial tube. n.-7.8 Vibratile flappers. 
L. ib. Body lobes. 0. Simple division of chymiferous tubes 
Lm. Lateral muscles. without tentacle in genus Ocyroé. 
M. mg.w. Median gelatinous prolongation near 
the otocyst. 
1-19. From Chun, op. cif., Pl. Il. figs. 9, 10; Pl. VII. figs. 1, 4, 6, 11; PI. VIII. fig. 4; Pl. IX. figs. 3, 
4, 8, 15, 16; Pl. XII. 3, 4, 6, 7, 8, 11. 
1-10. Development of Chiaja (Zucharis) multicornis. 
. Segmented ovum, showing the larger cells, ‘vitelline cells” within, surrounded by smaller cells of epiblast. 
The opening through which the larger cells appear is a blastopore. 
. Embryo in which the epiblastic cells have almost completely closed the opening (bp) seen in figure 1. The 
remains of this orifice appears as a long narrow slit. 
. Optical section of the gastrula. 
. The gastral mouth now completely closes, and the wall of the epiblast begins to infold to form the future 
mouth and stomach. 
Embryo in which this infolding has assumed considerable size, and in which, also, the tentacular promi- 
nences (ta) have begun to form. An otocyst is already formed, while a single otolith is represented in Chun’s 
figure, which has not yet grown into the otocyst. The investing layer is the epiblast. hb. Endoderm, 
hypoblast. At the point mu. is the beginning of the muscular layer which later becomes very prominent. 
n. Vibratile row of flappers. cil’. Tufts of cilia. 
. Still older larva in which the size of the layer between the outer thin epiblast and the larger cells, hypo- 
blast (2 b1., 2 b.4), has increased greatly in size. In the latter the star-like muscular cells can be seen. 
