MEDUSAE OF WOODS HOLE REGION. 49 



Obelia pyriformis (A. Agassiz.) 



Eueope pyriformis A. Agassiz, North American Acalephse, 1865, p. 88, 



Laomedia pyriformis Leidy, Murine Invertebrate Fauna Now Jersey and Rhode Island, in Journal Academy Sciem 



Philadelphia, 1855, p. 6. 

 Obelia pyriformis Haeckel, System der Medusen, 1879, p. 175. 



Medusa flat, discoid, with LM tentaclesat birth; gonads also present, at this period, pear-shaped 



and borne on proximal half of radial canals. ( (tocysts s ewhat largerthan in some of the preceding 



species and usually slightly to one side of the tentacular base. Manubrium globular with simple 

 mouth devoid of lobes or lips. 



Development. — From hydroid of same name, having its habitat chiefly on eel-grass nr in similar 

 surroundings. 



Distribution. — Somewhat general throughout the region. 



Obelia fusiformis (A. Agassiz.) 



Eucopi (?) fusiformis A. Agassiz, North American Acalephx, 1865, p. 90. 



Eucopt (?) divaricata A. Agassiz, op. cit. p. 91. 



Obelia fusiformis Haeckel, System iter Medusen, 1879, p. 177. 



Medusa very similar to former species, but with 48 tentacles at birth, when also the gonads are 

 well developed and of fusiform shape along the length of the radial canals. Manubrium quadrate in 

 shape, with four-lipped mouth. 



Ikithipmeiil. — From hydroid of same name. 



Distribution. — Massachusetts Hay. Nahant (Agassiz). 1 have not identified this medusa from the 

 Woods Hole region, and there may he a question as to its specific distinctness, since Agassiz has him- 

 self expressed doubt on this point. 



TIAROPSIS L. Agassiz I 1849 I. 



Tiaropsis diademata L. Agassi/.. Text cut. 



Tiaropsis diadt mala I.. Agassiz, Memoirs America n Academy Arts and Sciences, Y<>1. 1 V, 1849, p. 289. Contributions Natural 

 History United States, Vol. IV, 1862, p. 30S. A. Agassiz, North American Acalephee, 1865, p. 69. Haeckel, System 

 der Medusen, lST'i, p. 188. 



Bell hemispherical, or low dome-like, about half as high as broad. 

 Marginal tentacles very numerous in maturity, though comparatively few 

 when the medusa is liberated. They are always short, forming a deli- 

 cate fringe upon the margin of the bell. Pigment spots occur at the bul- 

 bous bases of the tentacles, and are probably ocellar in character. Eight 

 Otocysts are present, distributed between the tentacles, '_' in each quadrant, 

 and between the radial canals, each containing black otoliths. The 

 velum is narrow and very delicate. Gonads spindle-shaped, disposed 

 beneath the median radial canal region. Manubrium very short, with 

 four fimbriated oral lobes. Ontogeny unknown. Tiaropsis diademata. After A. 



Colors. — Bell pale bluish milky tint, gonads darker. Agassiz. 



Distribution. — Massachusetts Bay, Boston Harbor; occasionally taken at Woods Hole, March to May. 



OCEANIA Peron & Lesueur (1809. ) 



Oceania as a generic term has been largely superseded by most European writers upon Hydrome- 

 dusse, and Haeckel has designated it as obsolete, merging the medusa; formerly classed under it into 

 other genera, as Epenthesis, or instituting new genera which better define the characters of those forms. 

 Several American authors have likewise abandoned the use of Oceania as a generic name, lint still 

 others, notably A. Agassiz and Mayer, have continued to use it in something of its earlier sense. To 

 the present, author it has seemed expedient to continue to use it, though recognizing its growing obso- 

 lescence. As at present defined by Agassi/, and Mayer, it would seem to differ from Epenthesis chiefly 

 in the presence of two octocysts between each two marginal tentacles, and in its larger number of the 

 latter. 



B.B. F.1904 — i 



