74 FOSSIL MEDUS 2. 
seems to correspond to that thinnest portion of the disk which lies outside of the geni- 
tal ring, between it and the disk rim, which is thickened by the reversed marginal lobes. 
Farther inward follows a thinner ring, which I designate a genital ring because 
I believe that I recognize with certainty sexual organs in it. In a favorable light 
seven contiguous crescentic facets can be recognized on one-half of the disk within 
the ring. They are directed with the convex side inward, the concave outward, and 
seem to repeat the wreath of marginal lobes, which are almost twice as large. Their 
number, in all probability, amounted to 16, and there seems to be no other possibility 
than to regard them as sex organs, as they agree exactly in form and position with 
like organs in other acraspedote meduse. The great number of these sex organs, 
together with their continuity and contiguity, may appear remarkable, since the Acras- 
pede usually possess only 4 or 8 genital glands. In this particular our medusa draws 
nearer to the craspedote forms, in which often a continuous ring is formed by a large 
number of tangent genital organs. In any case this conspicuous circumstance appears 
sufiiciently important, according to the general custom ruling in the systematic study 
of medusie, to consider our fossil as a representative of a new family among Acraspede. 
From the notch between each two genital glands, radially to the corresponding 
peripheral notch, runs a straight line which can not be otherwise interpreted than as 
a radial canal. 
In the central cireular field, which is inclosed by the genital ring, we would 
expect to find the mouth and its surrounding mouth arms. However, the visible por- 
tions of this area are so obscure, and the drawing of their boundary lines is so faint 
and confused, that we should prefer not to give any definite opinion upon it. The 
only figures which are somewhat clear are two sausage-shaped mounds lying near each 
other on the periphery of the central field. In any case, the oral arms must have been 
quite short, or otherwise one at least would project out over the genital ring. 
As a résumé we have 8 eyes, 8 bunches of tentacles, 16 genital glands, 16 radial 
arms, and probably 4 simple oral arms. On the other hand, nothing definite has been 
determined regarding the form of the mouth, of the stomach, and of the system for 
procuring food which radiates from it. It is, therefore, not possible to determine 
sharply the whole generic character of our medusa. This much can be deduced from 
the form of the well-developed marginal lobes and their sufficiently recognizable struc- 
ture, that it belongs to that division of the higher medusze which Eschscholtz called 
Phanerocarpe, and Gegenbaur, Acraspede. In any case, it must belong to that great 
group with a simple mouth and 4 (or 8) oral arms which Agassiz assembled together 
as Semostome and compared with Rhizostome. 
After a somewhat full comparison with the forms of the Semostome, 
Dr. Haeckel concludes with these remarks: 
Under these circumstances we can not enroll our medusa with the Sthenonide, 
which stands the nearest among living medusz, but must regard it as the representa- 
tive of an especial, extinct semostomous family, which we call Eulithotidz and char- 
acterize in the following manner: Tentacles grouped in bunches, 8 eyes, disk rim lobed, 
16 sex glands. 
