MEDUSA OF WOODS HOLE REGION. 39 



LIZZIA Forbes I 1S4SI. 



Liizzia grata A. Agassi/.. PI. I. t i -_r - -I. 



//::/.( grata A. Agassiz, Proceedings Boston Society of Natural History, Vol. IX. 1862, \>. 99. Fewkes, Bulletin Museum 



Comparative Zoology, Vol. VIII, 1881, p. 1 12. A. Agassiz, North American Acalepha:, l-".">, p. 161. 

 Wargellium gratum Haeckel, System der Medusen, 1879, p. 95. 



Bell subcorneal with high, rounded apical projection. Marginal tentacles in 8 clusters, perradial 

 clusters with usually 5 tentacles, interradials usually 3 in mature specimens, fewer in young. There 

 an- no ocelli. Manubrium of moderate size with 4 rather prominent oral lobes, which air slightly 

 branched, Gonads form prominent clusters mi the basal portion of the manubrium. 'Phis medusa, 



like DysmorpJiosa fulgurans, produces lusse by asexual budding from the body 'if tin- manubrium. 



Specimens are found with secondary medusa in all stages of development. Like the species just 

 cited, this form .Iocs not seem to produce*sexual products ami medusse at the same time. 



Ontogeny. — So faras known to mo the hydroid stock of this medusa has not been traced. The 

 phases in medusoid budding have been studied by Haeckel, Agassiz, Fewkes, and Forbes, and 

 observations have been made by Claparede \'/.v\\. f. Wiss. Zool.,Bd. Xi on the development of the 

 egg. The tentacles arise first from the perradial points.:; from each; this is followed by the appear- 

 ance of a single tentacle at each of tin- interradial points, to which arc added later 2 more tentacles; 

 finally 2 tentacles are added to each of the primary sets. It should he noted, however, that this rule 

 has exceptions, considerable variation appearing in both the- number and the order of appearance of 



the tentacles. 



('t,hi iv. — Bell very transparent, tentacular bases pinkish, tending to brown ami even blackish in 

 rare cases. 



Distribution. — Fairly common throughout the region. (Nahant, Massachusetts bay. A. Agassiz; 

 Newport, Fewkes. ) 1 have repeatedly taken this medusa at Woods Hole, both in the Open tow and 

 with a small dip net in the eel pond. April to August. 



BOUGAINVILLIA Lesson (1836). 



Bougainvillia carolinensis (McCrady), PI. 11. ti'_ r . 4. 



Hippocreru carolinensis McCrady, Proceedings Elliott Society Natural History, Vol. I. 1857, p. 164. 



Ifargelis carolinensis L. Agassiz, Contributions Natural History United States, Vol. IV. 1862, p. S44. A. Agassiz, Nortli Ameri- 

 can Acalepha:, 1865, p. 156. 

 Btmyainvittia carolinensis Airman, Monograph Gymnoblastic Hydroids, 1871, p. S16, 

 Margelis carolinensis Haeckel, System der Medusen, 1879, p. 89. 



Bell subsplierical, with very thick walls of great transparency; radial canals 4. very narrow. 

 Marginal tentacles in 4 clusters of from 2 to 1"> each, varying with age, arranged about a finely pig- 

 mented triangular base. Velum well developed; manubrium rather long and with dichotomously 

 branching oral tentacles; gonads borne on walls of manubrium. 



Ontogeny. — The medusa is derived directly from the hydroid of the same name. When first lib- 

 erated the medusa is small, with nilher thin-walled, hemispherical bell, and but 8 radial tentacles, 2 

 ateach point. As growth takes place the bell becomes spherical and the mesoglea becomes greatly 

 thickened, particularly over the aboral region. The oral tentacles, which at first are single, soon 

 bifurcate, and this process repeats itself about three times, forming a somewhat complete series of oral 

 tentacles. The adult medusa is from S to 10 mm. in diameter. 



( ;,l,nv.— The triangular pad from which the tentacles originate is bright reddish with green borders, 

 the ocelli as many as the tentacles, forming a crescent of black points. The manubrium is of similar 

 colors, pinkish about the base, bordered with green and with streakings of the same colors running 

 lengthwise. There i>, however, great variation in the color markings on this medusa. 



Distribution. — Com n generally throughout the region, though chiefly limited to shallower 



waters, where the hydroid evidently Finds favorable environmental conditions. June to September. 



