Pacific Species of "Lar” — Hand 
53 
Blanco, Oregon, on the south and at a dis- 
tance of from 40 to 200 miles from shore. 
This plankton was collected by the Scripps 
Institution of Oceanography as part of its 
work on the California Cooperative Sardine 
Research Program. All the specimens ob- 
served possessed four first order radial canals 
and were in adult or nearly adult condition. 
The diameter of the bell varied from 6 to 10 
millimeters and the height from 6 to 8 
millimeters. They possessed from 40 to 72 
tentacles. 
The branching of the radial canals is very 
complex and highly irregular although the 
number of terminal branches in each quadrant 
is nearly equal on^any given specimen. Thus, 
on a specimen possessing 72 tentacles, the 
quadrants had 17, 18, 18, and 19 tentacles, 
123(32 34143 424 
Fig. 1. a-c, Probosddactyla occidentalis; d-f, P. cir- 
cumsabella; and g-k, P. flavicirrata, showing (diagram- 
matically) the branching of the radial canals. The 
numbers in figures a to /refer to the order of the canals 
and tentacles. The spots between the ends of the canal 
branches in figures g to j represent the position of 
tentacles to which no canals could be seen to be 
branching. 
respectively. This condition is illustrated by 
Figure Ig-/ It will be noted that a canal 
branch does not run to each tentacle. In most 
specimens it appeared that the tentacles were 
more numerous than the canals, which con- 
dition may or may not actually exist, as the 
specimens examined were badly contracted 
and it was difficult to determine the distribu- 
tion of the radial canals. In one specimen an 
anomalous condition was found in which the 
canals from two adjacent quadrants had ana- 
stomosed (Fig. Ik). 
Cnidothylacies (nematocyst sacs) are pres- 
ent on the exumbrellar surface and are con- 
nected to the solid ring canal by a chord of 
what are presumed to be endodermal cells. 
In many specimens no ring canal can be found, 
and here the chord of cells merely ends where 
the canal used to be. Uchida and Okuda 
(1941) noted that the ring canal of this species 
degenerates as the medusa matures, whereas 
Browne (1906) suggested that the disappear- 
ance of the ring canal was not unexpected, 
as each tentacle is directly connected to the 
stomach via the system of branched canals. 
The cnidothylacies never occur in association 
with the first order tentacles but can be found 
above all other tentacles and in the interten- 
tacular spaces. Most specimens, however, 
show a somewhat irregular distribution of 
these structures, and the greatest number ob- 
served in any one quadrant was 14. 
When this medusa is adult the gonads ap- 
pear as white to creamy (formalin-preserved 
color) folded masses covering most of the 
stomach. The four gonadial masses present 
occupy interradial positions, each mass being 
developed as a pair of thickened lobes upon 
the adradial sides of the quadratic stomach 
with a thin sheet of gonadial tissue connecting 
the two lobes and covering the stomach wall. 
The gonads do not appear to fuse across 
the radial margins of the stomach. The lips 
of the manubrium are highly folded and hang 
but a short distance below the oral end of the 
gonads. Figure 2 illustrates the several fea- 
tures just mentioned. 
