ANTHOMEDUSJE HYBOCODON. 39 



Hybocodon prolijer (hydroid and medusa), AOASSIZ, L., 1861, Cent. Nat. Hist. U. S., vol. 4, pp. 143, 343, plate 133, figs. 10, 



11; plate 25, 19 figs. 

 Hybocodon proltffr, AGASSIZ, A., 1865, North Amer. Acal., p. 193, figs. 325-328. ALLMAN, 1871, Monog. Tubul. Hydroids, 



p. 422. VERRILL, 1873, Invert. Animals, Vineyard Sound, p. 736, plate 38, fig. 282. BOHM, 1878, Jena. Xritschr. fiir 



Naturw., Bd. 12, p. 195, taf . 7j figs. 7-9. NUTTING, 1901, Bull. U.S. Fish Commission, vol. 19, p. 341, fig. 76. HARGITT, 



1904, Bulletin Bureau of Fisheries U. S., vol. 24, p. 33, plate 2, fig. 2; 1901, American Naturalist, vol. 35, p. 580, fig. 39; 



Ibid., 1902, vol. 36, p. 552; 1901, Biol. Bulletin Woods Hole, vol. 2, p. 222. PERKINS, 1904, American Naturalist 38, 



p. 516 (simultaneous sexual and asexual reproduction). 

 (?) Hybocodon prolijer, BROWNE, 1896, Proc. Zool. Soc. London, p. 466. 

 Hybocodon prolifer + H.annulicornis + ? Amphicodon fritillaria+ ? A. giobosus + A.amphipleurus, HAKCKEL, 1879, Syst. JerMcdu- 



sen, pp. 33, 35, 36, 37, taf. I, figs. 7-9. 



(?) Amphicodon fntillaria, BROWNE, 1895, Trans. Liverpool Biol. Soc., vol. 9. 



(?) Amphicodon grtnidum, LINKO, 1905, Zool. Anzeiger, Bd. 28, p. 215 (simultaneous sexual and asexual reproduction). 

 (?) Hybocodon prolifer, BROWNE, 1905, Proc. Roy. Soc. Edinburgh, vol. 25, p. 752. 

 Non Hybocodon prolijer, BONNEVIE, 1899, The Norwegian North Atlantic Expedition, 1876-1878, vol. 26, Hvdroida, p. 28, plate 



i, fig. 6. 

 Hybocodon prolijer, HARTLAUB, 1907, Nordisches Plankton, Mr. 12, p. 98, figs. 94-97. MULLER, H., 1908, Zeit. fur wissen. 



Zool., Bd. 89, pp. 62, 73 (origin and structure of the eggs). 

 ( ?) Hybocodon gravidum + H. islandicus + H . amphipleurus, HARTLAVB, 1907, Nordisches Plankton, Nr. 12, pp. 104, 106, 



figs. 99, 100. 



The following description is derived from studies made of medusae from the southern 

 coast of New England, United States: 



Adult medusa. Bell about 2.5 mm. high and 2.2 mm. wide. It is asymmetrical, the side 

 bearing long tentacles being longer than the other sides; or as Browne aptly describes it, 

 the margin is not at right angles to the longitudinal axis of the bell, but slopes toward the side 

 bearing the cluster of long tentacles. The 4 radial-canals are of lengths corresponding to 

 the sides of the bell. The canal leading to the cluster of long tentacles is the longest; while 

 the canal diametrically opposite to this is the shortest, the 2 other canals being of inter- 

 mediate length. There are 3 small, rudimentary tentacle-bulbs, I at the foot of the shortest 

 canal, and I at the foot of each of the intermediate canals. The cluster of tentacles at the 

 foot of the long radial-canal has wide, hollow, tapering basal bulbs. The mam shaft of each 

 tentacle is, however, slender, cylindrical, and contractile, and is annulated at regular intervals 

 by well-developed clusters of nematocysts. Young medusae commonly have but a single long 

 tentacle, but as growth proceeds they sometimes develop another and finally a third; and 

 all 3 grow to be of equal length, and form a conspicuous cluster. A number of medusa-buds 

 in various stages of development arise from the sides of the hollow base of the one or more 

 long tentacles, near the bell-margin. These medusa-buds themselves develop a single long 

 asymmetrical tentacle even before the bud is mature. When ready to be set free they resemble 

 the parent medusa in that they are sometimes observed to be developing a third generation 

 of medusae upon their tentacle-bulbs. 5 longitudinal lines of nematocyst-cells extend from 

 the bases of the tentacles to near the apex of the bell. 3 of these rows arise from the bases 

 of the 3 rudimentary tentacles, and extend up over the surface of the exumbrella immedi- 

 ately over the radial-canals. In addition to these there are 2 rows which start from the base 

 of the well-developed tentacles, and extend upward over the exumbrella surface on both 

 sides of the long radial-canal. The velum is well developed. The radial-canals are narrow 

 and straight. The manubrium is a simple tube, which usually extends about two-thirds 

 the distance from the inner apex of the bell-cavity to the velar opening. The mouth has 

 4 short lips with their edges surrounded by nematocysts. The mature eggs are found in the 

 ectoderm of the stomach, and there they develop into actinula larvie before being set free. 

 The entoderm of the tentacle-bulbs is intense orange. The rows of nematocysts upon the 

 exumbrella often display an orange tinge, as does also the entoderm of the stomach. 



Hydroid. The hydroid was found in Massachusetts Bay. growing in tide-pools where 

 the water was very pure. Stems about 50 mm. in height. They grow singly, or in small clusters, 

 and do not branch. Each stem terminates distally in a single large polypite. The stems 

 are not more than I mm. in diameter at the base, gradually enlarging toward upper end, 

 and are about 3 mm. in diameter at base of polypite. They are covered with a delicate sheath 

 of chitinous perisarc, which widens and displays several well-developed annulations near 

 the base of the polypite. The polypite is flask-shaped with a very broad base; the mouth is 

 situated at the extremity of a narrow cylindrical neck, which is capable of much distension. 

 There are 2 oral verticils, each composed of about 1 6 tentacles. The tentacles of the row 



