MEM. M. C. Z., IX. No. 3.— ACALEPHS, POLYPS. Wi 
11-13. Cunina rhododactyla. From Metschnikoff, op. cit., Pl. V. figs. 1, 2, 7. 
11. Youngest observed ‘‘cunina bud,” found in the gastric cavity. Perhaps developed from an egg. The long 
projection upward, with solid hypoblastic axis, is a tentacle. There are two layers, and a gastric cavity in 
; the body. 
12. The same, still older, with two tentacles and a mouth opening already formed. In stages intermediate 
between this and figure 13 there is little change besides the addition of new tentacles and the growth of a 
© stolon” from the middle of the disk. From this stolon, when there are twelve tentacles, buds develop. 
13. A larva with two buds (gm'. and gm.) on the stolon. The oldest bud (gm.) has two tentacles and an open 
mouth. The second bud has no tentacles. While the fate of these buds is unknown, the original medusa, 
upon which the budding has ceased, was observed to develop into a medusa resembling the parent. 
14-17. Cunina octonaria, MeCr. From McCrady, Description of Oceania (Turritopsis) nutricula, nov. spec., 
and the Embryological History of a singular Medusan Larva, found in the cavity of its Bell, Pl. VI. 
figs. 20, 27 ; Pl. VII. figs. 32, 33. 
14. Larval Cunina, found hanging in the bell cavity of Modceria ( Turritopsis) nutricula, McCrady. ga. Stomach 
opening through a long, flexible, tube-like body, through a terminal mouth (or). ta. Tentacles by which 
the larva hangs. 
15. A still older larva, in which the umbrella (wr.) and the otocysts (0 cy.) have begun to form. Four tentacles 
have developed from the body in place of the two already formed. ga. Stomach. or. Mouth. 
16. The young medusa now leaves the bell cavity of its host, and escapes in the form here represented. Seen from 
below (oral). ga. c. Gastric chamber. man. Manubrium. ocy. Otocyst. ta. Tentacle. ubr. Umbrella. 
This stage may be called the Ephyra stage. 
17. Side view of the last. ocy. Otocyst. ta. Tentacle. wbr. Umbrella. 
18-20. Development of Cunina rhododactyla. 
18. A stolon taken from its attachment to the tongue of Carmarina hastata, with medusa buds in all conditions 
of growth. 
19. From Uljanin, O WPOMCXOMR TENT RYAN TWOURYIONMIXCH Bh REAY TRG TEPIOHILTD. 
H36CTIA UMMEPATOPCKATO OBILECTBA JIOBUTEIEI ECTECTBOSHAHIA, AHTPOIO- 
JOTI W 8THOPPA®IN. MOCKBA. 1876. PL I. fig. 9. A similar but smaller stolon, with many 
attached meduse before liberation from attachment. a1. Points of attachment to the ‘‘ tongue” of the 
Carmarina. 
20. From Hieckel, op. cit., Pl. VI. fig. 76. A bud which has loosened its attachment to the stolon and become 
free (Ephyra stage). ga. Stomach. x. Nerve. ocy. Otocyst. or. Mouth. ta. Tentacle. tb. Tube (?). 
ubr. Umbrella. vel. Velum. 
21-36. Development of Geryonia. From Fol, Die erste Entwickelung der Geryoniden eies, Jenaisch. Zeitsch., 
Vol. VII. Pl. XXIV. figs. 1, 2, 3, 5, 6, 7, 11, 12, 13, 15; Pl. XXV. figs. 16, 17, 18, 19, 23, 24. 
21. Fertilized ovum with spermatozoa (sp.) in the mucus envelope. pli. Folds in the egg membrane. mn. Nucleus. 
epl. Epiplasm (upper plasmic layer). pl. Hypoplasm (lower plasmic layer). vé. mm. Vitelline membrane. 
d. Mucus covering. 
22. The first plane of segmentation, dividing the ovum into two segmentation spheres. epl. Epiplasm. 
hpl. Hypoplasm. nl. Cell nucleus. 8. Protoplasmie dots arranged in star rays. 
23. Embryo after the formation of a second plane of segmentation. epl. Epiplasm. hpl. Hypoplasm. 
nl. Nucleus. pli. Folds in the membrane of the egg. ve. Vacuoles between the spheres. vt. m. Vitel- 
line membrane. 
24. Embryo after the formation of the fourth plane of segmentation, consisting of sixteen cells. A segmentation 
cavity is found within, into which opens a hlastopore (b/p). x7. Cell nucleus. ve. Row of vacuoles. 
25. The ovum after the formation of the fifth plane of segmentation, consisting of thirty-two cells. The process 
of cell division, known as delamination, has begun in this embryo. U/p. Blastopore. ve. Row of vacuoles. 
Each of the thirty-two segments is divided into two unequal parts, of which the smaller is formed of gran- 
ular, and the larger of granular and transparent protoplasm. In the next stage a division of the thirty-two 
larger cells takes place, and in each of these a line separates the granular from the transparent protoplasm. 
The sixty-four masses of lens-like shape, composed of granular protoplasm, thus formed, go to make up an 
outer epiblastic layer, while the thirty-two masses of transparent protoplasm form the hypoblast. 
26. The ovum after the sixth plane of segmentation. It consists of thirty-two small cells, external (e p/), and 
thirty-two large cells (hp?). se. cav. Segmentation cavity. Already the division of the cells (¢ pl) into 
o, o!, has begun. 
