SKMA KOSTOME/E — DESMONEMA. 593 



Demonema gaudichaudii Agassiz. 

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Chrystiora gaudichaudii^ Lesson, 1829, Voyage dc la Corjuillc, Zooph., p. 114, Zoophytes planche 15, fig. I. 



Coitthoiivia petidiila and Medora capensis, A(;assiz, L., i86z, Cont. Nat. Hist. U. S., vol. 4, pp. u8, 163. 



Desmonema giiudichaudi, Agassiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 166.— HAtcKCL, 1880, Syst. dc-r Mcduscn. p. 527. 



Coutbouya gaudichaudi, Maas, 1908, Expcd. Antarctique Franjaise, Meduses, p. 5, planchc i, fig. i. 



Bell at least 500 or 600 mm. wide, only 5 to 7 tentacles in a sin<;lc line, in each inter- 

 rhopalar cluster. Thus when the medusa is of a greater size than ]). chicrchiinin, it has fewer 

 tentacles. Maas states that the color of the gastric cavity is brownish-purple, accentuated 

 in the gonads, while the muscle-system is lighter and the gelatinous substance is bluish and 

 transparent. The medusa is found in the Antarctic region in April. Future studies will 

 probably demonstrate that D. chierchiana is only a variety of this medusa for they are alike 

 in all respects exceptnig that m Desmonema cluerchiana the tentacles arise in several rows, 

 whereas ni D. gaudichaiuln they remam as a single row even when the medusa is much larger 

 than D. chierchiana. This difference may be due to environmental causes, or may be of 

 the nature of a variation such as one observes in the development of tentacles in Dactylometra 

 and Chrysaora, but until further studies have been carried out it will be safer to keep the 

 two forms speciticalh- distmct one from the other. It is probable, however, that D. i;aitJi- 

 chaudii is only a variety in which the tentacles remain in a single row, as in the young of I). 

 chierchiana (see fig. 376). 



Further details of the structure of D. gaudichaudii may be obtained from the description 

 of D. chierchiana which follows. 



Agassiz's Medora capensis is apparently a young stage of this medusa. 



Desmonema chierchiana Vanhoffen. 



Desmonema chierchiana, Vanhoffen, 1888, Bibliotheca Zoologica, Bd. I, Heft 3, p. iS, taf. I, fig. 4; 1908, Deutsche Sudpolar 

 Expedition, 1901-1903, Bd. 10, Zool. 2, p. 41, taf. 2, fign. 2, 3; Abbild. 5-9. — Browne, 1908, Trans. Royal Soc. Edinburgh, 

 vol. 46, p. 244, plate 2, fig. 2. 



{??) Chrysaora gaudichattdiij L.ESSOS, 1829, Voyage de la Co^H/Z/f, Zooph., p. 114, planche 13, fig. r. 



Umbrella jio mm. or more wide and 100 mm. high. Exumbrella smooth. The 8 pairs 

 of ocular lappets are onlv about one-third as wide as the 8 tentacular lappets, which are flatter 

 than a semicircle in outline. The 16 small, ocular lappets are bluntly rounded and sharply 

 set off from the 8 tentacular lappets. The subumbrella is divided into 16 equal sectors cor- 

 responding to the 16 stomach-pouches. These sectors are areas in which the circular muscles 

 are well developed and separated one from another by narrow septa. 8 of the 16 muscular 

 sectors are in the radu ot the 8 marginal sense-organs and 8 are intermediate. There are no 

 radial-muscle strands. 



There are 8 groups of tentacles, each of which, in old medusae, arises in several rows 

 from the subumbrella at some distance inward from the bell-margin. These tentacles are 

 developed along the outer edges of the 8 interocular, circular muscle-sectors. There are 

 about 60 tentacles in each cluster, the oldest and longest being along the innermost, and the 

 shortest and youngest in the outermost rows. The rows are not U-shaped, as in Cyanea, but 

 are nearly straight. The tentacles are hollow, their entoderm being thin and the ectoderm 

 thick-walled. When young the tentacles are somewhat flattened and the ectodermal longi- 

 tudinal muscle strands are set within infolded, gutter-like lines down the length ot the ten- 

 tacle. As growth proceeds these gutters sink deeper and deeper into the ectoderm and finally 

 become inclosed tubes, sunken beneath the surface. Thus the longitudinal muscles become 

 tubular strands of fibers. A full description of the tentacles is given by Vanhoffen, 1908. 

 When expanded the tentacles of a large medusa may be at least 20 meters long. 



The 4 mouth-curtains are well-developed and resemble those of Chrysaora. They are 

 narrow near the mouth-opening but expand outwards and then taper gradually to a point. 

 Each mouth-curtain is 1.5 times as long as the bell-radius and its margins are much folded. 



The 4 sac-like, protrusive gonads are folded and resemble those o( Cyanea, but are smaller. 



There are 16 sectors of circular muscles in the subumbrella, 8 in the ocular and 8 in the 

 interocular radii. These circular muscles do not extend beyond the zone of the clusters ot 

 tentacles and sense-organs and are not found in the subumbrella of the lappets. There are 

 no strands of radial-muscles in the subumbrella, or in the lappets, such as are seen in Cyanea. 



