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MEM. M. C. Z., IX. No. 3. —ACALEPHS, POLYPS. 
IPI ANAND, WGI 
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Development of the Hyprorpa, continued. Figures from Louis AGassiz. 
Mouth. 
Pigment. 
Polyp. 
Tentacle of the hydroid. 
Inside (around the mouth) row of 
hydroid tentacles. 
Radial tubes. 
Tentacles. 
Tentacular bulb cavity. 
Enlargement of the tentacle at the 
union with the border of the bell. 
Chymiferous tubes. 
Tube which lies in the same portion 
of bell (spheromere) as that from 
which the tentacle hangs. 
Umbrella. 
Velum. 
Vitellus. 
Vitelline membrane. 
Inverted external wall. 
Projection of the umbrella near the 
margin. 
Chitinous perisare. 
Ferule-like enlargement of the perisare. 
Hydroid head. 
Vitelline membrane. 
C. can. crc. Cireular canal. O. or. 
cau. Cavity. P. pig. 
E. eb. Epiblast. Py- 
eb. gm. Epiblastic bud. py. ta. 
ex. man. External wall of the manubrium. py. ta’. 
ex. ta. External wall of the tentacle. 
ex. vel. External wall of the velum. SRaanetos 
F. fa. Constriction in umbrella. TT. ta. 
G. ga. Stomach. ta’. 
gm. Bud. tab. 
H. hb. Hypoblast. 
hb. gm. Hypoblastie bud. th.— tb®. 
I. i. man. Internal wall of the manubrium. tb. ta. 
1. ta. Internal wall of the tentacle. 
i. vel. Internal wall of the velum. 
1. W. Internal bell wall. U. ubr. 
M. man. Manubrium. V. vel. 
man’. Confluence of the manubrium and bell. vt. 
mds. gm. Medusa bud. vt. m. 
ZTE SIR t Successively formed medusa buds. X, a}, 2. 
3 mds. gin. & 
m. w. Middle wall. 
N. nel. Nucleolus. 0. 
ni. Nucleus. 6. 
O. ocl. Ocellus. | r. AA. 
The figures on this plate were arranged by A. AGASSIZ. 
1-23, from Agassiz, Contributions to the Natural History of the United States, Vol. III. 
Pls. XVII. figs. 2, 11, 12; XVIII. 1, 2, 3, 4, 5, 6, 10, 11, 12, 14, 158. Vol. LV. 
Pl. XXV. figs. 2, 2%, 3, 4, 5, 9, 12, 13, 14, 15. 
1-16. Coryne mirabilis, Ag. 
1. Ovum. nel. Nucleolus. x7. Nucleus. vf. Vitellus. vf. m. 
2. A medusa bud just beginning to form. 
hb. gm. Outer and inner layer of the bud. 
eb. and hb. Outer and inner layer of the hydroid. 
eb. gm. and 
8. Bud little older than the last; ‘stretched longitudinally.” ¢b.and 6. Outer and inner layers of the hydroid. 
eb. gm. and hb. gm. Outer and inner layers of the bud. ¢b. Beginning of the system of chymiferous 
4, 5. 
6. Older bud showing chymiferous tubes from the side and face. ¢%. Epiblast of hydroid. 
It will be noticed that the latter would seem to be the 
tubes. 
Buds more advanced in age, in the latter of which radial tubes have developed, two of which are shown in 
profile. 
the hydroid. hb. gm. Hypoblast of the bud. 
epiblast. I think it is either hypoblastie or a third layer, — the gelatinous layer (mesoblast ?). 
tb’. Chymiferous tube in face. 
miferous tube in profile. 
eb. and hb. Outer and inner layers of the hydroid. 
Chymiferous tube. 
hb. Hypoblast of 
tb. Chy- 
