LEPTOMEDUS.E — TIAROPSIS. 259 



much flatter and broader, tentacles increase greatly in number, and gonads develop upon the 

 4 radial-canals. 



This medusa appears in vast numbers along the coast of New England in March. It 

 develops very rapidly and spawns in April and May. After the middle of May it becomes very 

 rare and is not seen during the summer months. The hydroid stock is unknown. Linko 

 records this medusa from the White Sea, northern Russia. 



Tiaropsis multicirrata L. Agassiz. 



Thaumantias multicirrata, Sars, 1835, Bcskriv og Jagttag., Bergen, p. 26, plate 5, fig. 12 a-c. 



Thaumantias melanops, Forbes, 1848, British Naked-eyed Medusae, p. 45, plate 10, figs. 3 a-d. 



Tiaropsis scotica, Allman, 1871, Monog. Tubularian Hydroids, p. 140, fig. 57.— Bohm, 1878, Jena. Zeitschrift fur Naturw., Bd. 



12, p. 183, taf. 2, fign. 15-30. 

 (??) Tiaropsis oligoplocama, Romanes, 1876, Journal Linnean Society London, vol. 12, p. 525; vol. 13, plate 15, fig. 4. 

 Tiaropsis multicirrata, Agassiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 355— Haeckel, 1879, s .Vst. der Mcdusen, p. 179.— 



Browne, 1895, Proc. and Trans. Liverpool Biol. Soc, vol. 9, p. 278; 1896, Proc. Zool. Soc. London, p. 481; 1905, Proc. 



Royal Soc. Edinburgh, vol. 25, p. 773.— Bedot, 1905, Revue Suisse de Zool., tome 13, p. 151 (citation of all literature 



1835-1850). 



This medusa is distinguished from the American T. diademata by the black entodermal 

 pigment of its tentacle-bulbs. 



Bell 20 to 30 mm. wide, 10 to 15 mm. high, with thick gelatinous walls and smoothly 

 rounded surface. 200 to 300 short tentacles about one-fourth to one-third as long as bell- 

 diameter. There is a small mass of black entodermal pigment constituting an "ocellus"( ?) in 

 base of each tentacle-bulb. There are 8 adradially placed marginal sense-organs, each com- 

 posed of an entodermal ocellus, and a crescentic chain of about 13 spherical concretions arranged 

 in a line in an open fold of the well-developed velum. There are 4 straight radial-canals. 

 The manubrium lacks a peduncle and has 4 folded, recurved lips. It is 4-sided and about 

 half to a third as long as depth of bell-cavity. The 4 gonads are linear, folded, and occupy 

 about three-fourths of the lengths of the 4 radial-canals, extending closer to bell-margin than 

 to sides of manubrium. Entoderm of gonads, stomach, and bell-margin dull-yellow. Ocelli 

 and pigment of tentacle-bulbs black. Found ofFthe coasts of England, Scotland, Helgoland, 

 and Norway near Bergen. Hydroid unknown. 



Browne, 1905, describes the young medusa, 1 mm. wide, from the Firth of Clyde, Scotland. 

 Bell-walls thin, bell-shaped, with 24 tentacles, 8 adradial marginal sense-organs, and no 

 gonads. 



This medusa appears to be relatively rare on the northwestern coast of Europe, and it has 

 never been taken along the American coast, where the genus is represented by the exceedingly 

 common T. diademata. 



Tiaropsis macleayi von Lendenfeld. 

 Tiaropsis macleayi, von Lendenfeld, 1884, Proc. Linnean Soc. New South Wales, vol. 9, p. 605, plate 32, fig. 37. 



Bell 12 mm. wide and 5 mm. high, somewhat flatter than a hemisphere, evenly rounded. 

 About 100 slender tentacles, not as long as bell-diameter. A few of these tentacles have each 

 a basal ocellus. 8 large adradial lithocysts with concretions situated between folds of inner 

 wall of hthocyst sac. Stomach quadrangular, prismatic, about one-third as long as depth of 

 bell-cavity. 4 very small lips. Gonads linear, upon proximal two-thirds of the 4 radial- 

 canals. Medusa light rose-colored. Gonads dark-red. Tentacle-bulbs and entoderm of stom- 

 ach brown. Tentacles nearly colorless. Found rarely at Port Jackson, New South Wales, 

 Australia, from April to July. 



Von Lendenfeld studied the early segmentation stages of the eggs of this medusa and 

 finds that the cell division is irregular and quite similar to that of Geryonia. 



Tiaropsis davisii Browne. 



Tiaropsis davisii, Browne, 1902, Annals and Mag. Nat. Hist., ser. 7, vol. 9, p. 281. 



Bell conical with moderately thick walls, 11 mm. wide, 8 mm. high. About 80 tentacles, 

 8 fairly large adradial sense-organs, each probably containing several concretions. Stomach 

 short, cross-shaped when contracted. Gonads form a thin, narrow band, extending nearly 

 whole length of the 4 radial-canals but not touching either margin or stomach. Found at 

 Stanley Harbor, Falkland Islands, 



