LEPTOMEDUS.E — .EQUOREA. 



333 



This medusa is found in the tropical Pacific. It is best described by Maas, 1905, from the 

 Malay Archipelago. Maas gives the following data for 4 specimens found by the Siboga 

 expedition in the Malay Archipelago, at Kabaena, and Salomakie: 



jEquorea macrodactyla Bigelow. 



Mesonema macrodactyla, Brandt, 1834, Recueil Actes seances publiques Acad. St. Petersbourg, p. 21 of the "separate." 



Mesonema macrodactylum, Brandt, 1838, Mem. Acad. St. Petersbourg, ser. 6, tome 4, Sci. Nat., p. 359, taf. 4.— Haeckel, 1879, 



Syst. der Medusen, p. 226— Goette, 1886, Sitzungsbcr. Akad. Wissen. Berlin, p. 833.— Maas, 1905, Craspedoten Medusen 



der Siboga Expedition, Monog. 10, p. 40, taf. 8, fign. 51, 54; 1906, Revue Suisse de Zool., tome 14, p. 96.— Chun, 1896, 



Mitt. Nat. Mus. Hamburg, Jahrg. 13, p. 7.— Bedot, 1905, Revue Suisse de Zool., tome 13, p. 139 (literature 1834-50). 



JEquorea macrodactylum, Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 174, plate 36. 



In common with other allied forms this medusa is very variable. 



The disk is a thick biconvex lens 20 to 45 mm., or more, wide. There are 10 to 30 ten- 

 tacles at the ends of some of the radial-canals. These tentacles are elongate, tapering, with 

 large, swollen, hollow basal bulbs. They are longer than the bell-diameter when expanded 

 and their basal bulbs are provided with excretory pores. There are 3 to 4 times as many 

 rudimentary tentacle-bulbs as tentacles; these are somewhat irregularly distributed around 

 the bell-margin. The lithocysts are more numerous than the tentacular rudiments and are very 

 small. Number of concretions ( ?) There are 60 to 100, or more, straight, simple radial- 

 canals. The stomach is very shallow and about half as wide as the disk, with 20 to 40 lips. 

 Gonads linear and developed on both sides of each radial-canal, leaving both ends of the 

 canals free; they begin to develop when the medusa is about 25 mm. wide and then they 

 often appear only on the older and wider canals, leaving the newly formed, narrow radial- 

 canals free of gonads until a later period. 



Entoderm of lips, radial-canals, and tentacle-bulbs milky in color, all other parts colorless. 



Widely distributed over the tropical Pacific, being found by Goette and Chun off the east 

 coast of Africa, by Maas in the Malay Archipelago, and by Agassiz and Mayer among the 

 Marshall Islands. The species has been most carefully studied by Maas, 1905, who presents 

 a table exhibiting its range of variation and also a good figure of the mature medusa. 



Bigelow, 1909, found 1 1 specimens of this medusa in the eastern tropical Pacific, and 

 states that when seen from without, the tentacle-bulbs are broadly triangular and extend in 

 a somewhat triangular or spur-like process up over the exumbrella surface of the bell. The 

 stomach-wall is of considerable breadth, but the mouth is apparently not capable of closing. 



Bigelow shows good reasons for believing that JEquorea maldivensis Browne is identical 

 with M. macrodactyla. (See page 330.) 



jEquorea pensilis. 



Medusa sp. Forskal, 1776, Icones rerum naturalium, p. 9, tab. 28, fig. B. 



Medusa caelum pensile, Modeer, 1791, Nova Acta Phys. Med., L. C. 8, App., p. 32, No. 32. 



JEquorea mesonema, Peron et Lesueur, 1809, Tableau Meduses, p. 336, No. 21. 



Mesonema ccelum pensile, Eschscholtz, 1829, Syst. der Acal., p. 112. 



Mesonema pensile, Haeckel, 1879, Svst - der Medusen, p. 226.— Browne, 1904, Fauna Geog. Maldive and Laccadive Archi- 

 pelago, vol. 2, p. 733, plate 55, fig. 4; plate 57, figs. 2-9; 1905, Report Pearl Oyster Fisheries, Gulf of Manaar, Roy.Soc. 

 London, Supplementary Report No. 27, p. 147, plate 2, figs. 11-15— Maas, 1905, Craspedoten Medusen der Siboga 

 Expedition, Monog. 10, p. 42, taf. 8, fig. 52. — Bedot, 1901, Revue Suisse de Zool., tome 9, p. 484; Ibid., 1905, tome 

 13, p.i39(all papers cited to 1850). — Bigelow, H. B., 1909, Mem. Mus. Comp. Zool. at Harvard College, vol. 37, p. 173. 



Rhegmatodes lacteus, Agassiz, A., and Mayer, 1902, Mem. Mus. Comp. Zool. at Harvard College, vol. 26, p. 147, plate 3, figs. 

 15, 16. 



Polycanna purpurostoma, Agassiz, A., and Mayer, 1899, Bull. Mus. Comp. Zool. at Harvard College, vol. 32, p. 169, plate 8, 

 figs. 26-28; Ibid, 1902, Mem. Mus. Comp. Zool. at Harvard College, vol. 26, p. 147. 



