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AGASSIZ AND MAYER: DACTYLOMETRA. 3 
fimbricated pennants trailing in long graceful curves far behind the 
medusa, and at other times they are drawn up into a shapeless mass 
about the medusa’s mouth. <A view of the free extremity of one of the 
oral fringes is given in Figure 30, Plate XI.; and a good idea of their 
general structure and appearance may be obtained from Figures 1, 2, and 
4. Small wart-like protuberances (Fig. 29, Plate XI.) are found scat- 
tered thickly over the outer surface of the oral fringes; they consist of 
clusters of nematocysts and red colored pigment granules. 
The plan of the stomach is represented in Figure 15, Plate VIII. It 
occupies a large space in the midst of the umbrella, and consists of a 
wide central cavity from which radiate outwards sixteen simple pockets 
(r, e”, r, 7”, ete). These pockets are separated from one another by 
sixteen radiating partitions or septw (rp, Figs. 6, 15, and 33), which 
join the upper and lower walls of the umbrella together. These radial 
partitions contain numerous muscle fibres, by the contraction of which 
the rhythmical movements of the bell are produced. From an inspec- 
tion of Figure 15 it will be seen that eight of the pockets (r,r, r) of 
the stomach lead out into the sense organs, and that the eight others 
(r’, r’, 7°) lead out into the tentacles ; indeed, the tentacles are hollow 
throughout almost their entire length, and their entoderm is ciliated 
exactly as is that of the stomach itself, 
The genital products are contained in four radially situated infold- 
ings of the oral wall of the stomach, and their position is marked upon 
the oral floor of the disk itself by the four deeply sunken sub-genital 
pits (gpt, Figs. 6, 14, 17, 18, 23, and 25). Figures 14 and 23 are 
somewhat diagrammatic sections of the medusa, intended to show the 
manner in which the genital organs fold inwards into the cavity of the 
stomach. Figure 14, Plate VIII., represents a section through the centre 
of the sub-genital pit and the pocket of the stomach ; while the section 
represented in Figure 23, Plate X., passes through the edge of the sub- 
genital pit, and through the centre of one of the septal partitions. A 
view looking down upon one of the genital organs, the exumbrella being 
removed, is given in Figure 17, Plate IX. In this figure part of the gen- 
ital epithelium is represented as torn away in order to show the opening 
of the sub-genital pit (gpt) lying below. It will be seen from an in- 
spection of Figures 14, 16, 17, and 23 that the genital organs are fur- 
nished with numerous gastric cirri (ge) which project inwards into the 
savity of the stomach. A view looking down upon the surface of the 
ovary is given in Figure 34, Plate XI., where we see the immature eggs 
of various sizes attached by peduncles to the ovarian wall. A section of 
