ANTHOMEDUS.E SARSIA. 53 



16 short tentacles which arise at irregular intervals from their sides. Each of these tentacles 

 ends in a knob-like cluster of nematocysts. The 2 or 3 medusa-buds arise from the sides of 

 the polypite between the tentacles. The stems of the hydroid are quite smooth, sparingly 

 branched, and about 12 to 15 mm. high. The stems are translucent, slightly horny in color, and 

 the polypites are light-red. 



I can not determine any well-defined distinctions between S. sarsii and S. mirabtlis, 

 excepting that in S. sarsn the medusa-buds appear always to arise from near the middle of 

 the sides of the polypite between the tentacles, whereas in S. mirabilts the medusa-buds arise 

 from near the base of the polypite at or below the level of the lowest zone of tentacles. 



Hartlaub has given excellent figures and descriptions of a number of medusae which are 

 closely related to Sarsia tubiilosa, if not mere varieties of the latter. These are S. pattersoru 

 Haddon, S. frutescens Allman, 5. decipiens Hartlaub, S. litorca Hartlaub, and S. pulchella 

 Forbes. (See Hartlaub, 1907, Nordisches Plankton, Nr. 12, pp. 29, 30, 32, 36; figs. 20-226, 

 23, 24, 28, 29.) I hesitate to quote these as distinct species, for I have observed the same 

 or nearly the same variations among individuals in swarms of S. mirabilis at Nahant, Woods 

 Hole, and Newport on our coast. A statistical study, or better still, a study of the respective 

 hydroids, is required before we can hope to determine these so-called "species" with certainty. 



Garstang, 1894, observes that the hydroid of S. tubulosa gives rise to dimorphic medusae, 

 as does S. mirabilis on the coast of New England, where early in the spring the medusae 

 are set free, whereas in May they mature while still attached to the hydroid. 



Sarsia tubulosa Lesson, variety Sarsia mirabilis L. Agassiz. 



Plate 3, figs. 2, 4, and 5; plate 4, figs. 1 and 2. 

 LITERATURE RELATING TO THE AMERICAN VARIETY or SARSIA TUBULOSA. 



Sarsia mirabilis, AGASSIZ, L., 1849, Mem. Amer. Acad., New Ser., vol. 4, p. 224, plates 4, 5. STIMPSON, 1853, Marine Invert. 

 Grand Manan, p. u. HAECKEL, 1879, Syst. der Medusen, p. 17. FEWKES, 1881, Bull. Mus. Comp. Zool. at Harvard 

 Coll., vol. 8, p. 141, plate 3, figs. 1 1, 12. LEVINSEN, 1893, Vid. Meddel. Nat. For. Kjobenhavn (5), Bd. 4, p. 143. BIR- 

 ULA, 1896, Annuaire Musee Zool. Imp. Sci. St. Petersbourg, tome I, p. 332. HARTLAUB, 1907, Nordisches Plankton, 

 Nr. 12, p. 37, figs. 30-40. LINKO, 1900, Mem. Acad. Sci. St. Petersbourg, ser. 8, vol. 10, No. 4, p. u, taf. I, figs. 1-12 

 (structure of ocelli); 1905, Zool. Anzeiger, Bd. 28, p. 212; 1900, Traveaul Soc. Jmperiale des Nat. St. Petersbourg, torn. 

 29, p. 151. 



Sarsia mirabilis (medusa), AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 21 1-217; vol. 3, Ibid., plate 18, figs. 15-250. 



Sarsia glafialis, MORCH, 1857, Beskriv af Gronland, p. 95. 



Corync mirabilis (hydroid), AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 185-21 1, plates 17-19; vol. 3, Jbid., figs. 1-16, 

 plate 17; figs. 1-14, plate 18; figs. 1-27, plate 19. 



Corvnt mirabilis, AGASSIZ, A., 1865, North Amer. Acal., p. 175, figs. 282-285. CALKINS, 1899, Proc. Boston Soc. Nat. Hist., 

 vol. 28, p. 336. 



Oceania lubulosa, GOULD, 1841, Invert, of Mass., p. 348. 



Syncorvnt mirabilis, ALLMAN, 1871, Monog. Tubul. Hydroids, p. 278. HARGITT, 1904, Bulletin Bureau of Fisheries U. S., vol. 

 24, p. 30, plate v, fig. i; 1901, Amer. Naturalist, vol. 35, p. 578, fig. 33; 1903, Science, vol. 16, p. 344 (variations). 

 HARTLAUB, 1905, Zool. Jahrbuchern, p. 526; Zool. Jahrb., Syst. Abth., 1901, Bd. 14, p. 356. TORREY, 1902, Univ. 

 California Publications, vol. I, p. 31. NUTTING, 1901, Bull. U. S. Fish Commission, vol. 19, pp. 328, 372, figs. 3, 81. 



( ?) Syndictyon angulatum (young medusa), MURBACH and SHEARER, 1903, Proc. Zool. Soc. London, vol. 2, p. 168. 



(})Sarsi barfnisii (young red-colored medusa), LINKO, 1905, Zool. Anzeiger, Bd. 28, p. 214 (north of Russia). 



( ?) Euph\sa tentaculata (abnormal medusa with only 3 well-developed tentacles), LINKO, 1905, Zool. Anzeiger, Bd. 28, p. 214 

 (Barents Sea, North Russia). 



Syncoryne densa, HARTLAUB, 1897, Wissen. Meeresuntersuch. Komm. Meere. Kiel, Helgoland, Neue Folge, Bd. 2, p. 452, taf. 

 166, figs. 4, u ; taf. i6r, figs. 7, 8 (hydroid forms dense tufts). Also: Sarsia sp., HARTLAUB, 1896, Verhandl. Deutsch. 

 Zool.Gesell., Leipzig, Bd.6, Vers., p. 182 (medusa; with branched manubria); 1907, Nordisches Plankton, Nr. 12, p. 26, 

 figs. 17-19, 22a (hydroid and medusa). 



The following description is derived from a study of medusae and hydroids obtained 

 off the southern coast of New England, United States. 



Adult medusa. Bell is half-egg-shaped, about 7 mm. in height and 4 mm. in diameter. 

 There is no apical projection, and the gelatinous substance is not very thick at the aboral 

 pole and becomes successively thinner near the margin. There are 4 long, highly contractile 

 tentacles, one at the base of each .radial-canal. The surface of each tentacle is covered with 

 prominent nematocyst-cells, which are clustered especially at the outer end of the tentacle. 

 Each tentacle arises from a well-developed basal bulb which contains a single ectodermal 

 ocellus upon the outer nerve-ring on the abaxial side of the tentacle-bulb. According to 

 Linko, 1900, the ocellus is composed of a cup-shaped invagmation of densely pigmented 

 ectodermal cells between which there are spindle-shaped bipolar nerve-cells. The ento- 



