574 MEDUS.E OF THE WORLD. 



Pelagia noctiluca var. "neglecta." 

 Pelagia neglecta, VANHOFFEN, 1888, Bibliotheca Zoologica, Heft. 3, p. 9, taf. 6, fign. 6-12. 



This variety is distinguished by the large, elliptical nematocyst-warts upon its exumbrella. 

 These warts are usually about twice as long as they are wide and display cross-furrows. Speci- 

 mens in which the bell is 53 to 60 mm. wide have a bell-height of 23 to 28 mm. Mouth-tube 

 15 to 25 mm. long and mouth-arms 68 to 85 mm. Color (?) This species is found at Naples 

 and at the Canary Islands. Were it not for the very large, elliptical nettle-warts of the exum- 

 brella, it would be identical with the typical Pelagia noctiluca Peron and Lesueur. It is so 

 closely related to P. noctiluca that I believe in view of the ordinary variability of individuals 

 of the same species in Scyphomedusae, it had best be omitted from further consideration and 

 merged with P. noctiluca. 



Pelagia cyanella Pe'ron and Lesueur. 



Plate 61, fig. I. 



Medusa pelagica, LINNE, 1758, Systema Naturae, Ed. 10, p. 660. 



Medusa pelagica, LINNE, 1766, Systema Nature, Ed. 12, p. 1098. 1788 (Gmelin), tomus I, pars 6, p. 3154. 



Pelagia cyanella, PERON ET LESUEUR, 1809, Ann. Mus. Hist. Nat. Paris, torn. 14, p. 349, No. 66. 



Dianaea cyanella, LAMARCK, 1816, Hist. Anim. sans vert., tome 2, p. 507. 



Pelagia cyanella, ESCHSCHOLTZ, 1829, Syst. der Acalephen, p. 75, taf. 6, fig. I. Bosc, 1830, Hist. Nat. des Vers., Ed. 2, tome 2, 

 p. 140, plate 17, fig. 3. AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 128, 164; Ibid., 1860, vol. 3, plate 12, 

 figs. 1-16. AGASSIZ, A., 1865, North Amer. Acal., p. 47, fig. 68. HAF.CKEL, 1880, Syst. der Medusen, p. 507. VAN- 

 HOFFEN, 1888, Bibliotheca Zoologica, Bd. I, Heft. 3, p. 22. BIGELOW, 1890, Johns Hopkins Univ. Circ., vol. 9, No. 80, 

 p. 66. HARGITT, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 70, plate 7, fig. I. 



This American medusa is very closely related to the European P. noctiluca, of which it 

 is apparently only a local variety. 



Bell about 40 mm. high and 50 mm. broad; somewhat fuller than a hemisphere, being a 

 little less broad at margin than a short distance above. Numerous small wart-like nemato- 



o 



cyst capsules are sprinkled thickly over the exumbrella and are especially thick in a zone at 

 about mid-height of bell; these protuberances are reddish in color and tend to be arranged in 

 radiating lines. 8 very long, highly contractile, hollow tentacles alternate with 8 marginal 

 sense-organs. Each sense-club is set within a niche between two adjacent lappets and is 

 protected on the outer side by a partial web between the lappets. The club is hollow and has 

 no ocellus, but contains a terminal, entodermal mass of crystalline concretions which are deeply 

 pigmented. 1 6 marginal lappets, hemispherical in shape. There is a long, narrow, 4-sided 

 proboscis, the radial corners of which extend downward as 4 long, flexible mouth-arms, the 

 free edges of which are complexly crenulated. The proboscis, together with the mouth-arms, 

 or palps, is about 3 times as long as bell-height. There are 4 complexly folded horse-shoe- 

 shaped gonads in mterradial positions upon the floor of the subuihbrella, and immediately 

 centripetal to them are 4 subgemtal pits or cavities extending inward from the outer surface 

 of the subumbrella. The quadrangular oesophagus leads into a circular, disk-shaped, central 

 stomach which gives rise to 16 radial pouches extending outward in the radii of the sense- 

 organs and tentacles. Each of these pouches gives off a pair of unbranched, curved canals 

 which enter the lappets, but do not form a ring-sinus. There are 1 6 well-developed strands 

 of radiating muscle fibers in the wall of the exumbrella adjacent to the gastrovascular cavity. 

 These extend outward in the radii of the tentacles and sense-organs, and fork as they approach 

 the bell-margin. 



The color is quite variable, sometimes bluish, sometimes slightly yellowish. Exumbrella 

 and mouth-arms sprinkled over with brownish-red nettling-warts, tentacles reddish-purple. 



This species is found among the West Indies and Florida Reefs, and in summer it may 

 drift northward in the Gulf Stream so as to appear off the southern coast of New England 

 from July to September. 



L. Agassiz, 1860 and 1862, found that the planulae of this species, as in P. noctiluca, 

 develop directly into medusae without going through a sessile scyphostoma stage and without 

 alternations of generations. The planulae are set free into the water where each develops into 

 a single medusa. The minute details of the development have been worked out upon Pelagia 

 noctiluca by Metschnikoff, 1886 (Emb. Stud, an Medusen, Wien.), and by Goette, 1893 

 (Zeit. fur wissen. Zool., Bd. 55, pp. 659-692). The gastrula is formed by invagination. The 

 first pair of radial stomach-pouches appear, according to Goette, as outpocketings from the 



