ANTHOMEDUS.E ECTO PLEURA. 69 



The discovery of Ectopleura pacifica and E. minerva makes it necessary to amend the 

 generic definition to include medusae with 2 as well as with 4 tentacles. 

 Ectopleura is distinguished from Zaticlea by its unbranched tentacles. 



Ectopleura dumortieri L. Agassiz. 



Plate 5, figs. 4, 5; plate 6, figs. I, i', 2. 



LITERATURE RELATING TO THE EUROPEAN MEDUSA. 



Tubularia dumortieri, VAN BENEDKN, 1844, Mem. Acad. Belgique, tome 17, p. 50, plate I. JOHNSTON, 1847, Hist. British 



Zoophytes, p. 50, plate 7, figs, i, 2. 



Ectopleura dumortieri, AC;ASSIZ, L. 1861, Cont. Nat. Hist. U. S., vol. 4, p. 342. 

 Eclofleura dumortieri, HINCKS, 1868, Hist. British Hydroid Zoophytes, p. 124. 

 Ectopleura dumortieri, ALLMAN, 1871-72, Monog. Tubularian Hydroid s, p. 424. BOHM, 1879, Jena. Zcitschrift fiir Naturw., 



Bd. 12, p. 198, taf. 7, figs. 10-13. HAECKEL, 1879, Syst. der Medusen, p. 22. 

 Non Ectopleura dumortieri, GRAEFFE, 1884, Arbeit. Zool. Inst. Wien, Bd. 5, p. 354. 

 Ectoflfura dumortieri, HARTLAUB, 1894, Wissen. Meeresuntersuch. Komm. Meere Kiel, Helgoland (i), Bd. I, p. 188. BROWNE, 



1905, Proc. Roy. Soc. Edinburgh, vol. 25, p. 748. 



Ectopkura dumortieri, HARTLAUB, 1907, Nordisches Plankton, Nr. 12, p. 94, figs. 90, 91. 

 Tubularia dumortieri, BEDOT, 1905, Revue Suisse de Zool., tome 13, p. 126 (citation of literature, 1844-48). 



LITERATURE RELATING TO THE AMERICAN MEDUSA. 



Ectopleura ochracea, A. AGASSIZ, in L. Agassiz's 1862, Cont. Nat. Hist. U. S., vol. 4, p. 343. AGASSIZ, A., 1865, North Amer. 

 Acal., p. 191, figs. 320-323. HAECKEL, 1879, Syst. der Medusen, p. 22. FEWKES, 1882, Bull. Mus. Comp. Zool. at Har- 

 vard College., vol. 9, p. 295, plate I, figs. 15, 16, 35, 36. NUTTING, 1901, Bull.U. S. Fish Commission, vol. 19, p. 373, fig. 

 82. HARGITT, 1904, Bulletin Bureau of Fisheries U.S., vol. 24^.32, plate 2, fig. I. AGASSIZ, A., and WOODWORTH, 1896, 

 Bull. Museum Comp. Zool. at Harvard College., vol. 30, p. 149, plate 6, fig. 6 (photograph of the medusa). 



Ectopleura, sp., HARGITT, 1908, Biol. Bulletin, vol. 14, p. 106, figs. 8-1 1. 



The finding of the hydroid of our American Ectopleura "ochracea" leads me to believe 

 that there are no specific differences between the European and American forms, and that 

 both should be called Ectopleura dumortieri, this being the older name. Hartlaub, 1907, 

 however, believes that E. dumortieri is smaller and has somewhat thicker bell-walls than 

 E. ochracea, but our American medusa varies considerably in these respects, as do also speci- 

 mens which I captured in the English channel in IQO". 



The following description is based upon a study of large numbers of specimens obtained 

 at Newport, Rhode Island, United States. 



Adult medusa. The bell is pyriform and is about 3 mm. high and 2.5 mm. wide. The 

 gelatinous substance is very thick and is especially so at the aboral pole. 8 longitudinal lines 

 of nematocyst-cells extend over the surface of the exumbrella from the basal bulbs of the 

 4 tentacles to the bell-apex, where they meet in a point. There are 4 equally developed, 

 short tentacles with large basal bulbs. The outer surface of these tentacles is thickly covered 

 with nematocyst-cells, and their distal ends are coiled in a close helix. Velum narrow. There 

 are 4 narrow, straight radial-canals and a simple, narrow, circular tube. The manubrium 

 is fusiform and extends not more than two-thirds the distance from the inner apex of the 

 bell-cavity to the level of the velar opening. There is no peduncle, and the mouth is a simple 

 round opening, the edge of which is armed with clusters of nematocysts. A short, blunt, 

 axial canal is often seen projecting upward from the stomach into the gelatinous substance 

 of the apex of the bell. The gonads are developed in the ectoderm encircling the stomach. 

 In brilliant specimens the tentacle-bulbs are yellow with a red core. 



The middle region of the entoderm of the manubrium is lilac-colored, the upper part 

 delicate yellow, and the lower end red or pink, but very often the medusa is dull purple or 

 dull brownish-purple. 



Hydroid. The hydroid shown in plate 6, figs. I, I'was found in August, in Newport 

 Harbor, Rhode Island, at a depth of about 10 fathoms. It is a Tubularian belonging to 

 the family Hyboconidas Allman, and is apparently identical with 'Tubularia (Ectopleura) 

 dumortieri of Van Beneden, 1844. 



The hydroid is about 25 mm. in length, and was found clinging to the stems of Obelia. 



The stems of the Ectopleura are isolated. Most of them are simple and unbranched, but 



occasionally they give rise each to a single side branch near the lower end. The lower end of the 



Ectopleura is coiled around the stem of the Obelia in a close helix. The stem of the Ectopleura 



6 



