HYDE: CAMAROPHORELLA. 63 
gested the possibility that these structures are only analogous and 
that the superficial similarity of the jugum in the several genera in 
which this t^'pe occurs, is not, as ordinarily considered, an indication 
of genetic relationship. It is true there is little to support such an 
idea, but it is thought best to make mention of it. The structure of 
the jugum of Camarophorella, a simple Jl- or A-shaped saddle between 
the primary lamellae, on which the remainder of the jugum is laid 
down as a single plate, evidently simultaneously throughout and not 
by a process of growth, is apparently so different from the simpler 
juga described for Merista and Meristella, that the resemblance may 
be superficial only. The apparent differences may be due, quite pos- 
sibly, to the more or less unsatisfactory material from which these 
structures have heretofore been worked out, as a result of which all 
the finer points have been missed, but it has served to suggest that 
we may have in this and possibly in other t^^^es of jugum, an example 
similar to that of the modern Magellania-like loop, the adult form of 
which is produced in several genera in different lines of development. 
That is, that the structure of the adult lophophore has been such as 
to demand a certain type of jugum and this has been developed in 
forms not nearly related, and that while the general shape of the adult 
structures might be the same, they might have been developed each 
through a different series of metamorphoses as in the modern Tere- 
bratelloids. As has been mentioned, Hall and Clarke have suggested 
such a dissimilar origin for the several genera with double-spiraled 
spiralia. 
In view of the little that is really known of the juga of Merista and 
Meristella, this can be taken as nothing more than a suggestion and 
the platforms found in the various genera of the subfamily indicate 
rather, that we should exjDect in the jugum of the earlier forms more 
detail than has yet been found. 
The question may well be raised : In how far do the facts know^i of 
the jugum of Camarophorella bear on the other tj-pes of jugum? 
It is not proposed to enter into such a discussion here, but it may be 
added that the jugum of Athyris lameUosa has been obtained from 
the same beds as the material herein described, preserved in exactly 
the same manner. It is very similar to the one figured on plate 6, 
and offers little suggestion as to its origin. The saddle is relatively 
better developed than in this figure and the stem is placed on its sur- 
face, just anterior to the posterior end, not quite terminally. It does 
