ANTHOMEDUS.E HYBOCODON. 41 



strup) and Norway (Sars). It is apparently widely distributed over the North Atlantic, 

 along the shores of continents and islands. It is rarely taken far from some coast. We 

 can not be certain that the American and European forms are identical until the hydroids of 

 both are discovered. 



Hargitt, 1904, states that the egg-cleavage is closely similar to that of Pennaria. Also 

 Browne, 1895, and Hargitt, 1902, 1904, find that the ova begin their development within 

 the walls of the manubrium of the medusa and are set free as actinulae. Muiler, 1908, and 

 Hargitt, 1904, find that the developing embryos within the walls of the manubrium absorb 

 their fellow ova, as has been observed by Doflein in Tuhularia mesembryanthcmurn, and by 

 Allen in T. crocea. Developing actinulae and budding medusae are abundant at Woods Hole, 

 Massachusetts, during the spring months. 



Hargitt, 1902, and Perkins, 1904, find that actinula larvae develop upon the manubrium 

 at the same time that medusa-buds are being set free from the tentacle-bulbs. When set free 

 the actinulae have 10 tentacles. The mouth and oral zone of tentacles develop only after the 

 actinula is set free; and appear at the pole which was adjacent to the parent medusa during 

 the attached period. Linko, 1905, also observed this simultaneous process of development 

 of medusa-buds and of actinula larvae in his " Amphicodon graviJum," which develops 

 actinulae with 1 1 tentacles. It is probably identical with H . prolifer. A single specimen was 

 found in Barents Sea, north Russia. 



H. Miiller, 1908, finds that the ova are large and amoeboid. Only about 2 eggs survive 

 to maturity in the ovary; the others having been devoured by the successful eggs. The 

 ooplasma is a network, the exoplasma being narrow-meshed and the endoplasma wider. 

 There are numerous pseudo-cells in degenerate stages, sometimes dividing amitotically. 



Hybocodon pendula Haeckel. 

 Plate i, fig. 2. 



Corymorpha nutans (hydroid), STIMPSON, 1853, Marine Invert. Grand Manan, p. 9. 



Corymorpha pendula (hydroid), AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 276, 343, plate 26, 6gs. 7-17. VERRILL, 



1873, Invert. Anim., Vineyard Sound, pp. 510, 736, plate 36, fig. 273. 

 Corymorpha pendula, HARTLAUB, 1907, Nordisches Plankton, Nr. 12, p. 85, fig. 81. NUTTING, 1 901, Bull. U.S. Fish Commission, 



vol. 19, pp. 337, 370, fig. 15. MAY, 1903, American Naturalist, vol. 37, p. 579, n figs, (histology and embryology). 

 Corymorpha pendula (medusa), AGASSIZ, A., 1865, North Amer. Acal., p. 192, fig. 324. 

 Hybocodon pendula, HARGITT, 1904, Bulletin Bureau of Fisheries U. S., vol. 24, p. 34, plate 2, fig. 3. 

 Hybofodon pcndulus (medusa), HAECKEL, 1879, Syst. der Medusen, p. 34. 

 Monocautus pendulus, ALLMAN, 1871, Monograph Tubularian Hydroids, p. 397. 



Adult medusa. Bell pyriform and about 5 mm. in height. It is relatively higher than 

 the bell of H. prolifer, and the gelatinous substance at the apex is much thicker. There 

 are 5 rows of nematocysts upon the exumbrella, as in H. prolifer. The basal bulb of the 

 well-developed tentacle is much smaller than in H. prolifer, and no medusa-buds have 

 been observed to arise from it. The well-developed tentacle is 2 to 3 times the length of the 

 bell-height. Its surface is studded with large, swollen rings of nematocysts, which give it 

 a heavy appearance. The tentacles at the bases of the 2 intermediate radial-canals are quite 

 well developed, and this is not the case in H. prolifer. The velum is wide and thin. The 

 radial-canals are narrow and straight. The manubrium is longer than in H. prolifer, and 

 extends a short distance beyond the velar opening. There is a small peduncle. The lips 

 are thickly covered with nematocysts. Pink pigment-granules are found in the entoderm 

 of the tentacle-bulbs. The entoderm of the manubrium is pink and lilac, and contains also 

 some pink pigment-granules. 



Hydroid. The hydroid (Corymorpha[Hybocodori\ pendula)\s found in depths of IO to IOO 

 fathoms off the New England coast, with its base buried in the sand. It is 80 to 125 mm. in 

 height, and 6 mm. in diameter at the widest part. It always grows singly and is never branched. 

 The mid-region of the stem is very thick and is covered with a canaliculated coenosarc, but 

 the basal end narrows considerably, as does also the region near the free upper extremity, 

 which is long, slender, and pendulous. The stem is anchored by a number of root-like, 

 tubular, fleshy processes. The perisarc exists only as a thin delicate film. The head of the 

 polypite is large and highly contractile. There is a single verticil of long, hollow tentacles 

 at base of polypite. The mouth is situated at the extremity of a large flask-shaped proboscis, 



