MKDUS^E. 13 



is Turris neglecta, Lesson (1837), and this Medusa is quite unlike any Catablema or 

 Tiara. It is genetically 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. eurystoma, 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 iveldoni has radial canals with long blind divertieula, 

 which are simply long lateral canals. It is probable that the very short divertieula 

 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: T. digitalis, Forbes (1848); T. coeca, Hartlaub (1902); T. pelagica, 

 Agassiz and Mayer (1902) ; T. breviconis, Murbach and Shearer (1903) ; and T. fontata, 

 Bigelow (1909). I do not intend to attempt a revision of the Tiaridae now, as it 

 would l)e no light undertaking, so must leave it for another occasion or for some 

 other student to accomplish. 



CATABLEMA WELDONI. 

 (Plate I., 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 large, 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 I., 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. Gouads just appearing in small folds along 

 the stomach. Two long, opposite perradial tentacles with filaments, and two very 



x 2 



