MEDUSA OF WOODS HOLE REGION. 69 



Umbrella fiat and discoid, with a central aboral convexity; marginal lobes 8, with 16 or more sec- 

 ondary lappets. Marginal tentacles very numerous, in 8 clusters composed of several series of rows, the 

 tentacles very long. This is one of the largest of our medusa', often reaching a diameter of several 

 feet, and with tentacles 50 feet or more in length when fully extended. The stomach is large, and 

 there are normally 16 gastric' pouches, 8 ocular, rather small and somewhat triangular, and 8 tentacular, 

 much broader. The gonads are massive, extending the genital pouches into pendulous sacs hanging 

 about the margin of the manubrium, which is long and with complex oral arms hanging in plaited 

 folds within the circle of tentacles. 



Cyanea, like Aurelia, presents numerous variations, not only in numerical and structural features, 

 hut in color, size, etc. 



Colors. — Umbrella brownish to purplish, alternating with areas of transparency over the exum- 

 brellar surface. Gonads yellowish white; tentacles variously colored, yellowish, orange, brown. 



Distribution. — Almost the entire coast from Maine to North Carolina or beyond. This species is 

 rather distinctively an arctic medusa, and is most abundant in early spring, though occasionally occur- 

 ring in midsummer. 



L. Agassiz has described two other species of Cyanea, namely, C.falvaand c versicolor, i havenol 

 been able to recognize any constant differences of sufficiently marked character to warrant the conclu- 

 sion o£ their specific distinctness. Collections made from a wide range of New England coast waters 

 and southward to the ( iulf Stream show every feature of intergradation among these supposed species 

 and the preceding so fully as to preclude any definite line of separation between them. It would seem 

 doubtful whether they were even entitled to varietal distinction, so intimate is the blending of varietal 

 characters among medusa' taken within the same region. 



Family PELAGII1)£. 



KHV TO THE OENEKA. 



1. Marginal tentacles 8; marginal lobes 1*5 Pefagia 



2. Marginal tentacles 24; marginal lobes 32 Chrysawa ' 



;:. Marginal tentacles 4U, less in young specimens; marginal lobes 4K Dactylometra 



DACTYLOMETKA L. Agassiz (1862). 



Dactylometra quinquecirra (Hesor). PI. VII, fig. 2. 



Pdaffia quinquccirrha Desor, Proceedings Boston Society Natural History, Vol. III. 1S4S, p. 76. 



Vacbtjlometra quinquecirra, L. Agassiz, Contributions to Natural History of United static, 1862,Vol. IV". pp. 125, 166. A. 

 Agassiz. North American Acaleplue, 1865. p. 48. Haeckel, System der Medusen. 1S79. p. 518. 



Umbrella rather high and arched aborally, much as in Pelagia, disk about three times as broad as 

 high. Manubrium long and pendulous, and with 4 slender oral arms, which are more or less frilled, 

 as in the preceding. Rhopalia 8, marginal tentacles 40, marginal lobes 48. The tentacles are arranged 

 in the adults with 5 between each 2 rhopalia. In immature specimens there arc usually but 3 in these 

 octants. Gonads in 4 masses within the gastric pouches, beneath each of which is a rather huge sub- 

 genital pit on the subumbrellar surface. In size this medusa varies in the adult from 80 to 150 mm. 

 in broad diameter. 



Colors. — In general, similar to those of Pelagia cyanella, though generally less brilliant, the various 

 hues being paler and somewhat more delicate. Exumbrella delicate bluish, mottled with reddish 

 brown, fading into yellowish; tentacles reddish to orange; oral arms pale pinkish, varying to bluish. 



Distribution. — Rather more limited than cither Aurelia or Cyanea. It is a common medusa at 

 Woods Hole, in Buzzards Bay, Vineyard Sound, and at Nantucket. 



Like several of the previous species, Dactylometra exhibits more or less variation. According to 

 Mayer (Bulletin Museum Comparative Zoology, XXXII, No. 7), the tertiary tentacles arise invari- 

 ably on either side of the ocular lappets. In several specimens examined during the summer of L902 

 they were found to arise at intermediate points between the primary and secondary sets. Again, 

 according to the same observer, the tertiary tentacles appear only as the medusa approaches sexual 

 maturity, and after attaining a diameter of 130 mm. On the contrary, I have found them well devel- 

 oped in specimens having a diameter of only 40 mm. and where no gonads were yet developed. The 

 variation in the number of marginal lobes also was found to be about the same as in the previously 

 mentioned species. 



