ANTHOMEDUS.E STEENSTRUPIA. 35 



careful comparative study of the hydroids of these forms must be made before we may safely 

 assert either that they are identical or separate species. 



The hydroid of S. rubra is Corymorpha nutans of Sars, and is common on sandy bottoms, 

 off the northern coasts of Europe, at moderate depths. The stems of the hydroid are 

 solitary, and are about 50 to 75 mm. high, and about 4 mm. wide at the widest part. The 

 whole stem is corrugated by numerous narrow longitudinal bands. The widest part of the 

 stem is usually at a short distance above the lower end. This lower end is bent sharply at 

 right angles to the main part of the stem and bears long, hair-like filaments which serve to 

 anchor the hydroid. There are also blunt, papilla-like processes which arise from the sides 

 of the stem above the bent portion. The polypite is large and flask-shaped, and has a basal 

 zone of 30 or more long, tapering tentacles, about as long as the polypite itself. In addi- 

 tion to these tentacles there are 6 to 7 closely crowded verticils of oral tentacles, which are 

 much shorter and thinner than the proximal. 15 to 20 branched peduncles arise from the 

 sides of the polypite close to the bases of the proximal circlet of tentacles, and bear the 

 medusa-buds. The hydranth is light-red, the stem being paler than the polypite. On the 

 English coast the medusa-buds are set free during the summer. 



Allman gives a good description of the hydroid. 



Steenstrupia aurata. 



Euphysa aurata, (medusa) FORBES, 1848, British Naked-eyed Meduss, p. 71, plate 13, fig. 3. 



Euphysa aurata (medusa)+E. mcditcrranea, HAECKEL, 1879, Syst. der Medusen, p. 32, taf. 2, figs. 8, 9. 



Euphysa medilrrranca, DU PLESSIS, 1888, Recueil Zool. Suisse, tome 4, p. 543. 



Euphvsa aurata (Forbes), BROWNE, 1895, Trans. Liverpool Biol. Soc., vol. 9, p. 248; 1896, Proc. Zool. Soc. London, p. 474. 



Euphvsa aurata, BROWNE, 1905, Proc. Roy. Soc. Edinburgh, vol. 25, p. 749. BEDOT, 1905, Revue Suisse de Zool., tome 13, 



p. 134. 

 Corymorpha nana, (hydroid) ALDER, 1857, Cat. Zooph. Northumberland and Durham, p. ill, plate 7, figs. 7, 8. HINCKS, 1868, 



Hist. British Hydroid Zooph., p. 130, plate 22, fig. 3. 



Corymorpha nana, HARTLAUB, 1907, Nordisches Plankton, Nr. 12, p. 81, figs. 76-78 (list of authors and localities). 

 (?) Euphysa virgulata, AGASSIZ, A., 1865, North Amer. Acal., p. 189, figs. 316-319. 



This medusa is found off" the Atlantic coasts of western Europe and in the Mediter- 

 ranean. Steenstrupia virgulata of Massachusetts Bay is probably identical with S. aurata. 

 For description of the European form, see synoptic table of characters of the species of Steen- 

 strupia. The European S. aurata appears to be smaller than the American S. virgulata. 



Steenstrupia virgulata = (?) S. aurata Forbes. 

 Plate i, fig. 6. 



(?) Steenstrupia aurata, FORBES, 1848, British Naked-eyed Medusae, p. 71, plate 13, fig. 3. 



Euphysa virgulata, AGASSIZ, A., 1865, North Amer. Acal., p. 189, figs. 316-319. HAECKEL, 1879, Syst. der Medusen, p. 33. 

 NUTTING, 1901, Bull. U.S. Fish Com m., vol. 19^.370. HARGITT, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 33. 

 Corymorpha virgu/aia, HARTLAUB, 1907, Nordisches Plankton, Nr. 12, p. 84, fig. 79. 



Adult medusa. The bell is pyriform, with a broad, dome-shaped apex. It is 5 to 12 mm. 

 in height, and 4.5 to 9 mm. in diameter. Surface of exumbrella smooth and without rows of 

 nematocysts. There are 4 tentacles, one at the base of each radial-canal; 3 of these are mere 

 rudimentary bulbs, but the fourth is large and conical. Its surface is thickly covered with 

 nematocyst-cells of large size. There are 4 simple, straight radial-canals, and a slender, 

 circular vessel. The velum is wide, with an indented, free edge. The manuhrium is cylin- 

 drical without a peduncle, and extends about half the distance from the inner apex of the 

 bell-cavity to the level of the velar opening. No apical, axial canal. The mouth is a 

 simple, round opening without prominent lips. The genital products are contained within 

 the ectoderm of the manubrium. Manubrium light-yellow. The entoderm of the radial- 

 canals near the bases of the tentacles is intense pink, and the ectoderm of the tentacles is 

 milky-white. This species was found by Dr. Alexander Agassiz, in Massachusetts Bay, at 

 Nahant, and is recorded from Woods Hole, Massachusetts, by Nutting and Har^itt. 



The figure here shown is reproduced by his kind permission from Dr. Alexander Agassiz's 

 drawing of the medusa. There is no difference between this medusa and S. aurata of Europe 

 except that the American form appears to be larger; but the hydroid of the American medusa 

 is unknown, and until this is discovered it will be impossible to determine the identity of the 

 American form. 



