20 EMBRYOLOGICAL MONOGRAPHS. 
8-15. From Allman, op. cit., Pl. VIII. figs. 3,7; Pl. IX. figs. 3, 4; Pl. XI. fig. 9; Pl XVIII fig. 4; 
Pl. XX. fig. 4. 
8, 9. Dicoryne conferta, Alder. 
8. “The female locomotive, ciliated sporosac, shortly after its liberation,” ‘‘as it appears when swimming.” It 
is viewed at right angles to the plane of its two tentacles. 
9. Longitudinal section (optical) of a female sporosac made at right angles to the plane of the tentacles, and 
viewed under slight pressure. 
10. Actinula of Tubularia indivisa., Linn. <A zodid homologous to a free medusa, which is formed in small 
spherical sacs, hanging from an axis, dependent between the tentacles of the hydroid. 
“The actinula, shortly after liberation. It is figured in the attitude assumed when moving from place to 
place ; the mouth is turned to the surface over which the actinula is moving, while some of the long 
tentacles are bent in the same direction, and are employed as ambulatory organs.” Allman. 
11. Clavatella prolifera, Hincks. An ambulatory larva, seen from the side, using its outstretched tentacles as 
walking organs. 
12. Young stage of a free medusa (gonophore) of Perigonimus. 
13. Young medusa of Bougainvillia, represented as it appears in motion. The bell walls are contracted, and the 
velum is pushed outward. 
14. An older (?) Bougainvillia, floating passively, with tentacles widely extended. Subsequent growth from a 
medusa in this condition into that of the adult takes place simply by an increase of the number of tenta- 
cles and eye-spots in the bundles at the beil-rim, and an additional complication of the lips. 
15. The same, older. 
16. Medusa of Oceania languida. From a sketch by Fewkes. 
The youngest stage of this gonophore. man. Manubrium. a. Tentacle. ¢b. Chymiferous tube. 
ubr. Umbrella. vel. Velum. 
17-18. Zygodactyla Groenlandica, A. Ag. From Fewkes, Studies of the Jelly-fishes of Narragansett Bay. Bud. 
Mus. Comp. Zoil. Vol. VIII., No. 8, Pl. V. figs. 5, 6. 
17. Youngest known medusa of this genus, seen from the oral side of the disk. caz. cre. Circular canal. man. 
Manubrium. ocy. Otocyst. 7. tb. Radial tube. r. tb’. Radial tube, which has not yet extended to the 
circular canal. ta. Tentacle. 
18. Same larva seen in profile. man. Manubrium. +. ¢b. Radial tube. r. ¢!. Intermediate radial tube, which 
has not yet extended to the circular canal. ocy. Otocyst. ta. Tentacle. The fully-grown medusa has a 
very large number of radial chymiferous tubes, otocyst and tentacles. 
19. Willia ornata. From A. Agassiz, op. cit., fig. 274°. Young gonophore in which the tubes have just begun 
to bifureate (7. b.). The youngest form has four undivided tubes, alternating with four simple bundles of 
nematocysts in the bell walls. 
20-22. Lizzia octopunctata. From Fewkes, Studies of the Jelly-fishes of Narragansett Bay. Bull. Mus. 
Comp. Zool., Vol. VIII., No. 8, Pl. I. figs. 1, 3, 6. 
20. Mother medusa, with buds in various conditions of growth forming on the outer walls of the proboscis. 
mds. gm. Medusa buds. The larger (mds. gm.) approximates in shape that of a medusa. Jab. Lip. 
ocl. Ocellus. or. Mouth. ta. Tentacle. whr. Umbrella. vel. Velum. 
21, 
bo 
2. Developed buds, with the form which they have when just escaped from the parent manubrium. 
21. Young medusa (oral view). cav. Bell cavity. ocl. Ocellus. ta. Tentacle. ubr. Umbrella. vel. Velum. 
22. Side view of the last. man. Manubrium, at the base of which are buds of a third generation. 7. tb. Radial 
tube. wbr. Umbrella. At the apex there is a canal which formerly afforded free communication between 
the cavity of the manubrium of the parent and that of the bud. The bud, when it severs its connection 
with the parent, has on the bell rim sixteen tentacles, consisting of four bundles of three tentacles each, 
and, alternating with these, four single tentacles. 
23. Young of Haliclystus (Lucernaria?) From A. Agassiz, North American Acalephe. Illustrated Catalogue 
Mus. Comp. Zoil, No. 2, p. 63. or. Mouth. uwbr. Umbrella. a. Base of attachment. 
23". A group of tentacles of the same, in different stage of growth. 
24°24. Schizocladium ramosum. From Allman, op. cit., p. 152. 
24%. “Part of an adult colony, magnified about six diameters.” a. A terminal part of a branch still invested by 
a chitinous perisare. £8. The perisare of this branch has been ruptured, while the contained eccnosare 
has protruded a little, and is visible at the extremity. ¢ The separation of a small body of ccenosare from 
