260 MEDUSAE OF THE WORLD. 



Tiaropsis rosea Agassiz and Mayer. 

 Plate JI, figs. 1-4. 



Tiaropsis rosea (young), Agassiz, A., and Mayer, 1899, Bull. Mus. Comp.Zool. at Harvard College, vol. 32, p. 1 68, plate 7, figs. 



21, 22. 

 Tiaropsis punctata, Mayer, 1900, Ibid., vol. 37, p. 49, plate 22, figs. 60-63; '9°4> Mem. Mus. Brooklyn Inst. Arts and Sci., vol. 



1, p. 14, plate 3, fig. 21. 

 Tiaropsis rosea, Maas, 1905, Craspedoten Medusen der Siboga Exped., Monog. 10, p. 30, taf. 7, fign. 45-47. 

 Tiaropsis diademata, Fewkes, 1882, Bull. Mus. Comp. Zool. at Harvard College, vol. 9, p. 277, plate 7, figs. 13, 14. 



Mature medusa. — Based on the description of a specimen by Maas, 1905, from Damar, 

 Malay Archipelago. Bell about 15 mm. wide and flatter than a hemisphere. There are 4 

 well-developed, perradially situated tentacles, with large, conical basal bulbs, sharply offset 

 from the lashes of the tentacles. These tentacles are shorter than bell-diameter. Besides these 

 4 well-developed tentacles, there are 28 short, rudimentary tentacle-bulbs, 7 in each quadrant. 

 The 4 interradial tentacle rudiments are larger than the others. There are 4 adradial sense- 

 organs which are similar in structure to those of other species of Tiaropsis. They consist of 

 an open fold of the velum containing a row of numerous, small, ectodermal concretions. Above 

 this pocket of the velum is a black ocellus in the entoderm of inner side of ring-canal. These 

 adradial sense-organs, the tentacle rudiments, and large perradial tentacles are spaced at 

 equal distances around margin. Thus in each quadrant there is a well-developed tentacle, 

 then, as one passes around the bell, there are 2 tentacle rudiments, then a sense-organ, then 3 

 tentacle rudiments, another sense-organ, then, finally, 2 more tentacle rudiments, and, lastly, 

 a well-developed perradial tentacle. There are thus 40 appendages (4 large, 28 rudimentary 

 tentacles, and 8 sense-organs) on bell-margin, all at equal distances (g°) apart. Velum quite 

 narrow. There are 4 straight, narrow radial-canals and a ring-canal. 



Stomach urn-shaped, wide, and 4-sided at its base, but narrower at its throat. It is 

 about half as long as depth of bell-cavity and the 4 lips have markedly folded edges. The 

 gonads are linear and occupy somewhat more than the middle thirds of the 4 radial-canals. 



Entoderm of stomach, tentacle-bulbs, and gonads ocher-yellow to dull-red. Ocelli black, 

 other parts colorless. 



A study of the medusae at Tortugas, Florida, inclines me to believe that the tropical 

 Atlantic and Pacific specimens are identical. 



Tiaropsis mediterranea MetschnikoflF, 1886, from the Mediterranean, is closely allied to 

 the tropical Atlantic and Pacific species, but is apparently separated by the fact that it be- 

 comes mature with only 2 well-developed, perradial tentacles, while the 2 that are 90 apart 

 from these large tentacles remain mere tentacle-bulbs. There is, however, considerable 

 variation in the development of the tentacles as compared with the size and maturity of the 

 medusa in specimens from Tortugas, Florida, and it is possible that future studies will show 

 that there is but one Tiaropsis living in the warmer seas, and this should be called T . medi- 

 terranea. 



Tiaropsis mediterranea Metschnikoff. 

 Tiaropsis mediterranea, Metschnikoff, 1866, Arbeit. Zool. Inst. Wien, Bd. 6, p. 239, taf. 22, fign. 6-8. 



Bell rounded, 7 mm. wide, 5 mm. high, with thick gelatinous bell-walls. 2 well-developed 

 tentacles with hollow, conical, basal bulbs; these are at the bases of 2 opposed radial-canals; 

 there are 2 smaller tentacles at bases of the other 2 radial-canals. Longest tentacles about as 

 long as bell-diameter. There are 5 small, rudimentary tentacle-bulbs in each quadrant. 8 

 adradial lithocysts, each with about 20 concretions, and an entodermal ocellus. 4 straight, 

 narrow radial-canals with 4 linear gonads on their distal two-thirds. Manubrium conical, 

 4-sided with 4 short, simple lips, not reaching to level of velar opening. Entoderm yellow. 

 Messina, Italy, in December. 



Genus COSMETIRA sensu Hartlaub, 1909. 



Cosmelira, Forbes, 1848, British Naked-eyed Medusa?, p. 42. — Hartlaub, 1909, Zoolog. Anzeiger, Bd. 34, p. 83. 



The old genus Cosmetira is synonymous with Laodicea, but Hartlaub, 1909, defines it in a 

 new sense to designate a medusa which was probably described by Forbes under the name 



T liauinantias pilosella. 



