28 EMBRYOLOGICAL MONOGRAPHS. 
18, 19. Agalma Sarsii. From Metschnikoff, op. cit., Pl. IX. figs. 15, 17. 
18. Larva, showing the connection of the embryonic appendages (primitive hydrophyllium and serrated hydro- 
phyllia) with the polypite and pneumatocyst (pn cy.), by means of an axis (8). Four serrated hydrophyllia 
are shown. The connection of the cavity C. P. Z. with that of the polypite is through an enlargement 
(ampulla a), into which the tubes of the several hydrophyllia appear also to open. The cluster of bodies 
at the base of the polypite, near its junction with the pneumatocyst, are embryonic tentacular knobs 
(figs. 23, 24). ga. Stomach cavity. or. Mouth. 
19. Larva about the same age as the last, turned in sucha way that a serrated hydrophyllium is shown in full 
face. The fore-shortened extremity of the tube (C. P. L.) of the primitive hydrophyllium is just visible. 
pr. hy ph. Primitive hydrophyllium. pig. Pigment at the base of the float (paph.). ga. Stomach. 
nt cy. Nematocyst. ‘y. Tube of the serrated hydrophyllium. 
20. Agalmna elegans. From Fewkes, Studies of the Jelly-fishes of Narragansett Bay. Bull. Mus. Comp. Zoil., 
Vol. VIII, No. 8, Pl. IX. fig. 2. 
“ Athorybia larva,” embryo with a ring of provisional serrated hydrophyllia (ser. hy ph.), and embryonic 
tentacle (em. ta.), with a provisional (?) axis. There is a remnant of a vitellus (vf.) which, in this species, 
does not pass into the polypite. Our species of Agalma seems to resemble Crystal/odes in its method of 
absorption of the vitellus. The pneumatophore (yn ph.) is permanent. pyt. Polypite. y. Median canal 
of the serrated hydrophyllium. 
21. From Metschnikoff, op. cit., Pl. XI. fig. 2. 
An embryo older than the ‘* Athorybia larva,” with the serrated hydrophyllia characteristic of that stage, 
and with embryonic tentacle (em. ta.). It has developed two neetocalyces at least (ne x.), a permanent 
axis (az.), permanent tentacular knobs, two of which are to be seen in the lower centre of the figure just 
above the letters (em. ta.). A radial tube (7. tb.) is developed in the tentacle, and the pneumatophore 
(pa ph.) approximates in shape that of the adult. 
22-29. From Fewkes, op. cift., Pl. IX. figs. 1, 9, 9%. Fig. 25, from sketch. 
. Larva still retaining, as an embryonic feature, the provisional tentacle and knob ; but in other respects like 
the adult. Provisional hydrophyllia lost, and in their place permanent covering-scales (hydrophyllia). 
Axis divided into two parts; that which bears the nectocalyx (zc.s.), called the nectostem, and that 
which bears the remaining appendages, the polyp stem (py. s.). The permanent tentacle, with knobs 
characteristic of the genus Agalina, coexists with the larval tentacle (em. ta.). Hydrocysts (iy cy.), with 
their filaments (fil. hycy.) present. mnewz!. Rudimentary nectocalyces. yn ph. Pneumatophore. pyt. A 
to 
bo 
polypite. 
23-24. Embryonic tentacular knob of Agalma elegans. 
23. Side view. 
24. Seen from below. 
25. Outline of an undeveloped hydrophyllium, not serrated, found in a larval Agalma elegans, a. Anterior 
(place of attachment). p. Opposite end. v. Ventral (side turned to the axis). 
26-29. Development of the tentacular knob of Physophora hydrostatica. From Fewkes, Contributions to a 
Knowledge of the Tubular Jelly-fishes. Bull. Mus. Comp. Zoil., Vol. VI. No. 7, Pl. 1. figs. 4, 5, 6, 7. 
26, 27. Young condition of the knob. ¢. vs. Embryonic vesicle, resembling the terminal vesicle of the adult knob 
in Ayalma. This is reduced in size, and lost in the adult Physophora. @. Enlargement of the cavity of 
the knob, which later grows into a canal (cn.) along the side of the coiled part of the adult knob, 
d. Point of origin of the coiled part of the knob. 
28. In this figure the vesicle (¢. vs.), formerly terminal, has become lateral (7. vs.), and the cavity (@) has been 
elongated into a canal (en.) by the growth of the point of attachment of the coiled part of the knob to the 
pole opposite its pedunele, or attachment to the tentacle. iv. Involuerum. sac. Saceulus. 
29. Knob similar to that of the adult. The lateral (embryonic) vesicle is lost, the canal (cn.) tube-like, and the 
attachment (\) of the sacculus to the inner wall of the inyolucrum at the opposite pole to that where it 
formerly hung. 
