AXTHOMKIHS K I'A( IIV( -iililiVLK. '_' I 



DESCRIPTION OF GENERA AND SPECIES OF ANTHOMEDUSjE. 



Genus PACHYCORDYLE Weismann, 1883. 



Pachycordylt, WEISMANN, 1883, Entstehung Seiualzellen Hydromedusen, pp. 87, 217. HAKI.II r, 1404, Mitth. Zool. Station 



Neapel, BJ. |6, p. 553. 

 Paminrmus, MAYER, 1904, Mem. Nat. Sci. Museum Brooklyn Institute Arts and Sti., v.il. i, No. i, p. 6. 



GENERIC CHARACTERS. 



Codonidae without tentacles, radial-canals, or circular vessel. Manubrium surrounded 

 by a ring-like gonad. The hydroid-stock is Pachycordyle. 



Except the medusas of Millepora, these are the most degenerate and short-lived of the 

 free-swimming Hydromedusae. They are even more degenerate than are the medusae of 

 Corymorpha and Pennaria, and may be compared with Eucopflla (R. von Lendenfeld, 1883, 

 Zeit. fur wissen. Zool., Bd. 38, p. 497) and Agastra (C. Hartlaub, 1897, Wissen. Meeresunter- 

 such. Biologisch. Anstalt auf Helgoland, Neue Folge, Bd. 2, Heft i, Abt. 2, p. 504, taf. 22, 

 figs. 5, 8 10). In these last-named medusae we find neither manubrium nor marginal tentacles, 

 hut there are 8 otocysts and a velum, and the radial and circular vessels are well developed. 



Pachycordyle weismanni Hargitt. 



Pachvcorii\lf lutnmannt, HAROITT, 1904, Mittli. Zool. Station Neapel, Bd. 16, Heft 4, p. 553, plate 21, figs. 1-8. 



( ?) Pachyconlyle napolilana, WEISMANN, 1883, Die Entstehung der Seiualzellen bei den Hvdromedusen, Jena, pp. 87, 217. 



Medusa pyriform, 2 mm. high, 1.3 mm. wide. Tentacles and marginal sense-organs 

 lacking. No radial-canals. Ring-canal a mere fissure with vestiges of an entodermal linin 

 near the margin. Velum narrow, with a small opening. Manubrium large, conical, and with- 

 out a peduncle. Ripe ova are in the entoderm, and are discharged very soon after medusa is 

 liberated. Mouth lacking. Manubrium orange or dark-brown, other parts colorless. The 

 medusa swims with a short, jerky motion, but lives only one or two hours. 



The hydroid is found in the Bay of Naples growing upon the shell of Fusus rostratits. 

 The colony arises from a delicate, reticulated hydrorhiza. Hydrocaulus sparingly branched, 

 3 to 8 mm. high. Perisarc dull yellowish-brown, not extending beyond base of the hydranth. 

 Hydranths club-shaped, with subconical hypostome. 8 to 16 irregularly arranged filiform ten- 

 tacles, delicate and thread-like when expanded. Body of hydranth orange or reddish, 

 hypostome whitish. Not more than 2 or 3 medusa-buds are borne on the side of the stem 

 of each budding polyp. Occasionally the medusa-buds develop on the side branches, more 

 commonly on the main stems. The ova originate in the entoderm where they remain until 

 discharged into the water from the manubrium of the medusa. This species may possibly be 

 the female torm of VVeismann's Pachycordyle napolitana. On Weismann's hydroid, how- 

 ever, there were no free medusae, only sessile gonophores. All of Weismann's specimens were 

 males, while Hargitt's were females, and it is possible, as Hargitt states, that the females 

 only give rise to free-swimming medusae. 



Pachycordyle degeneratus. 



Plate I, fig. I. 



Paroanemu* degtneretui t MAVFR, 1904, Memoir-. N.it. Sn. Museum Rrooklvn Institute of Art^. and Sci., vol. i. No. i, p. fi, plate 

 ',. "H- " 



Bell thin-walled, about 0.75 mm. high and 0.3 mm. in diameter. Bi-ll-walls quite rigid, 

 velum powerful and well developed. There are neither tentacles, radial-canals, circular 

 vessel, nor marginal sense-organs. Manubrium spindle-shaped, and about a third as lon 

 as height of bell. Fluids within the stomach-cavity are maintained in rapid motion, appar- 

 ently through the action of cilia. Near aboral end of bell is a deep conical cicatrice which 

 apparently marks the place of last connection between the medusa and its hydroid stock. 

 Bell is translucent and milky in color, while manubrium is cream-colored. Only 5 specimens, 

 all males, were found in Nassau Harbor, Bahamas, on the nights of July 18 and 19, 1903. 



