92 FOSSIL M¥DUSA. 
essential part of the mid-field, and the radial and circular furrows as only 
bounding it. The zone wis not a velum, but the protuberance (Ausguss) 
of the umbrella surface. The outer parts are due to the thickness of the 
disk, which first formed a projection, then a fold. The projection would 
explain the existence of the furrow p; the fold, partly filled with mud, that 
of the ridge s. ; 
The “rosette” is a branched stomach. In view of this character, this 
species appears to be related to the craspedote family of the Aquoridze 
(AEginia, Cunina, Eurybia), which have 8 broad gastral branches, and also 
Fic. 23.—Medusina deperdita. Reproduced from Dr. Brandt's figure, which he describes as follows: 
s, a sharp and distinct peripheral ridge, of a circular shape; p, circular furrow; wu, ring zone; c, inner furrow; 
m, depressed mid-field; 7, radial extension of the furrow c. The lobes of the rosette are of two sizes, alternately large 
and small. The larger lobes show slight excavations at their periphery as if it were the beginning of fission. m is the 
ceelenteric cavity. The eight lobes of the rosette are only additional pouches of the central cavity. wu is the projection 
of the umbrella disk; not a velum. 
In order to comprehend the details of the peripheral portions of the impression from their origin, one can perhaps 
imagine that the umbrella rim was thrown inward (orally), so that it formed first a circular projection and later an out- 
ward fold. The projection then would explain the existence of the furrow p, and the fold filled with ooze the existence of 
the ridge s. 
lack an oral trunk and tentacles, which appear to be lacking in Acalepha 
deperdita also. However, the latter can not with certainty be referred to the 
ZEquoridz, for in the recent form the gastral ramifications are long, not 
short, and, furthermore, are all equal, while in A. deperdita they are alter- 
nately large and small. 
