Miinrs.K in 



is Turriii neiflectu, Lesson (1837), and this Mctlusu is (juito unlike any Ctttuhleinn or 

 Tiara. It is gcnerically ilistinct from 7'urris- dit/italif of Foilics and from the other 

 species whifh have been recently added to the genus Turris. 



In the genus Cata/jlema Haeckcl placed three species — namely, C. vesiairiuin 

 (A. Agassiz, 1865), C. campanula, Ilaeckel, 1879 (the earlier references to Medusa 

 caiiipnnuld of Fahricius, 1780, are perfectly useless), and C. (turystiniiii, Ilaeckel, 1877. 

 I think that the above three species may with safety he united untler the name of 

 ('atahleina vesicaruun. Dr. Maas (1U04) has already liukcil (J. cainpamda, Hneckel, 

 to C. vesicariiDii. It is clearly an Arctic Meilusa, which nccasionally ilrifts into the 

 North Atlantic. Catablana icelduni has radial canals with long blind diverticula, 

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

 present in C. vesicariuin are rudiments of long lateral canals. 



In the genus Turris the following species have radial canals with diverticula or 

 •a jagged edge: T. dii/itiilis; Forbes (1848); T. cui-ca, Ilartlaub (1902); T. pelai/ica, 

 Agassiz and Mayer (l'J0i3) ; T. hrnvictniix, Murbach and Shearer (1903) ; and T. funtata, 

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

 would be no light undertaking, .so must leave it for another occasion or for some 

 other student to accomplish. 



C A T A IJ L E M A W K L D O N I. 



(Plate I., figs. 1-5.) 



De.scription of tlie Species. — Umbrella .somewhat licli-shapcd, 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 maigiu. 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. (jonads 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 havitig 

 on the inner side a .series of iilaments with nematocysts. One small marginal bulb 

 between every two tentacles. 



Sice. — Und)rella up to .30 mm. in height. 



Description of an Early Sbuje (Plate I., fig. 1). — I'mbrdla .somewhat bell-shaped, 

 with a rounded summit, and fairlv thin walls, about as high as broad. Velum 

 narrow. Stomach .■■mall and .'^om<!\vhat (|uadrangular. .Mouth with four rather long 

 lips and a slightly fohled margin. Four fairly bnuid i.idial canals, each witli aliout 

 Ifi pairs of short, simple diverticula, variable in length, but not branched. Circular 

 »«nal rather narrow, without <liverticula. (ionads just appearing in small folds idong 

 the stomar;h. Two long, op[)osite perra<lial tentacles with filaments, and two very 



.\ 2 



