MEDUSA. 13 
is Turris neglecta, Lesson (1837), and this Medusa is quite unlike any Catublema or 
Tiara. It is generically distinct from Turris digitalis of Forbes and from the other 
species which have been recently added to the genus Turris. 
In the genus Catablema Haeckel placed three species—namely, C. vesicarium 
(A. Agassiz, 1865), C. campanula, Haeckel, 1879 (the earlier references to Medusa 
campanula of Fabricius, 1780, are perfectly useless), and C. ewrystoma, Haeckel, 1877. 
I think that the above three species may with safety be united under the name of 
Catablema vesicarium. Dr. Maas (1904) has already linked C. campanula, Haeckel, 
to C. vesicarium. It is clearly an Arctic Medusa, which occasionally drifts into the 
North Atlantic. Catablema weldoni has radial canals with long blind diverticula, 
which are simply long lateral canals. It is probable that the very short diverticula 
present in C. vesicarium are rudiments of long lateral canals. 
In the genus Turris the following species have radial canals with diverticula or 
a jagged edge: 7. digitalis, Forbes (1848); 7. coeca, Hartlaub (1902); T. pelagica, 
Agassiz and Mayer (1902); T. breviconis, Murbach and Shearer (1903); and 7. fontata, 
Bigelow (1909). I do not intend to attempt a revision of the Tiaride now, as it 
would be no light undertaking, so must leave it for another occasion or for some 
other student to accomplish. 
CATABLEMA WELDONL 
(Plate L., figs. 1-5.) 
Description of the Species—Umbrella somewhat bell-shaped, with a rounded 
summit and thick walls, a little higher than broad. Velum narrow. Stomach large 
and globular, occupying the upper half of the umbrellar cavity. Mouth Jarge, with 
four short lips and a closely folded margin. Four broad radial canals; each with 
about 20 pairs of long diverticula or branches, at right angles to the radial canals, 
variable in length and shape, and usually branched. Circular canal broad, with a few 
rudimentary diverticula. Gonads in eight longitudinal rows, extending along the 
whole length of the stomach, each row consisting of a series of transverse folds. 
About 24 long tentacles, evenly distributed round the umbrellar margin, each having 
on the inner side a series of filaments with nematocysts. One small marginal bulb 
between every two tentacles. 
Size—Umbrella up to 30 mm. in height. 
Description of an Early Stage (Plate L, fig. 1).—Umbrella somewhat bell-shaped, 
with a rounded summit, and fairly thin walls, about as high as broad. Velum 
narrow. Stomach small and somewhat quadrangular. Mouth with four rather long 
lips and a slightly folded margin. Four fairly broad radial canals, each with about 
16 pairs of short, simple diverticula, variable in length, but not branched. Circular 
canal rather narrow, without diverticula. Gonads just appearing in small folds along 
the stomach. Two long, opposite perradial tentacles with filaments, and two very 
Xx 2 
