594 The American Naturalist. [July. 
otocysts are wanting on the bell margin, as in Anthomedusse, the 
sexual bodies hang from the radial tubes on the bell as in Lepto- 
medusae or Oceania-like genera. In most respects, save the 
simple position of the sexual bodies, Polyorchis is however a true 
Tubularian. 
The youngest form of Polyorchis which was found betrays 
clearly the affinities of the adult, since it shows that the side 
branches from the radial tubes are in 
. reality structures of comparatively 
I' later growth in the development of 
the Medusa. The accompanying 
figure represents an undeveloped or 
young individual of Polyorchis before 
the side branches of the tubes had 
formed, and before the tentacles had 
reached any considerable length. Like 
the younger forms of many young 
Medusae of widely different genera 
^- we find clusters of small bodies 
t superficially resembling nematocysts 
^ g, ~ ' strewn over the external surface of 
I the bell. The immature Medusa has 
no apical prominence on its bell, and 
in general its umbrella is more elong- 
^^^- ^' ated, with a longer vertical diameter, 
Young Polyorchis. , ' , , . ,, r i-u 
than the adult. All stages of growth 
between the young represented in Fig. 4 and the adult can be 
easily collected. 
There is another very curious Medusa likewise belonging to 
the Anthomedusse, which is found in the vicinity of the Island 
of Santa Cruz. ^ This Medusa is so remarkable that a figure of it 
is introduced for comparison with related representatives from 
the Atlantic coast. 
One of the most interesting genera of Tubularian Medusae 
1 The island of Santa Cruz is the nearest of the Santa Barbara islands to the city of 
