12 Goel. 
CCELENTERATA. 
gastral cavity itself) are dilations of the stomach, in whose inferior 
wall, separating them from the sub-genital cavities, the ovaries and 
spermaries are developed from the endoderm ; the sexual products are 
carried away, normally through the mouth ; and the four sub-genital 
cavities (scarcely developed in Chrysaora^ wanting in the new genus 
Discomedusa, but developed again in Ehizostomidca) have no intimate 
relation with the organs of generation, being perhaps properly respiratory 
in their principal function. The marginal corpuscle is an eye (at least an 
organ for the perception of light), but the hood-like lobe covering it 
contains a peculiar (olfactory ?) organ of sense ; nervous elements 
(fibrils and ganglionary cells) are present in the immediate vicinity of 
this organ, in the pedicle of the corpuscle, at its base, in the ocular sinus, 
as a double ganglion; they are also found in the transversely striated 
muscles of the marginal zone of the disk, while the non-striated muscular 
elements of the arms and tentacles have the character of ectodermal 
“ neuro-muscular ” cells ; the theory of the ambiguous character of these 
elements is however contested and restricted within its proper limits j 
the same cell may be differentiated into one of the two (nervous or con- 
tractile), but not into both. Cnidoblasts are not only found in the ecto- 
derm, also in the endoderm, e.g. the gastral filaments. The hermaphro- 
ditism of Chrysaora (at least in certain seasons) is confirmed, but not 
entirely cleared up. Claus found small males, large and middle-sized 
hermaphrodites, and large females, showing vestiges of previous herma- 
phroditism ; the spermaries are developed from the endoderm, in small or 
larger vesicles, on the inside of the arms and stomach, on the gastral 
filaments and the gastro-genital membrane, »&:c. 
The author finally discusses the relations of Lucernaria, Charybdea, and 
JEgina with the true discophorous Acalephs {Medusae with gastral fila- 
ments), and arrives at the conclusion that the JEginidee are true Hydrome- 
dusce, while the Lucernariidee and Charyhdeidee should be arranged with 
the Acale^hce {Monostomece and Rhizostomece) as primary divisions of this 
sub-class, viz., Cylicozoa and Lobophora. 
Nausithoe, Koll., is upheld as a good but imperfectly known genus. 
Melanaster and Polybostricha are not different from Chrysaora. A now 
genus is introduced as Discomedusa^ type of a new family intermediate 
between the Aureliidee, Pelagidce^ and Rhizostomidoe. Disk flattish ; 
four single fimbriated arms ; mouth wide ; no special gastro-genital 
sacs; sub-genital cavities also wanting; sexes distinct; organs of 
generation forming a simple, almost closed ring. Margin of disk and 
tentacles (twenty-four) as in the Pelagidce ; eight ramifying and anasto- 
mosing (ocular) radial canals, and eight simple (tentacular) vessels, some- 
times united by a few branches with the vascular net, all of equal 
length and united by the circular canal. Differs from Aurelia in 
the want of gastro-genital and sub-genital cavities, the shape of the 
genital bands, the number and non-dorsal development of the tentacles 
and consequently the want of a“ velum”; and in the margin of the disk 
not being formed through the development of intermediary lobes, but 
through subdivision of the primary Ephyra-\o\)Q^. D. lobata^ sp. n. (pp. 
1 1 & 42-47, pis. viii. & ix.), Trieste. 
