MEIM's.i: i>k WOODS HOLE REGION. 31 



Tliis medusa was first described by McCrady from Charleston Harbor. The only record of its 

 subsequent occurrence within that region is that by Fewkes above cited. For several years I have 



taken medusse at W Is Hole which differ in no essential respect from Met Irady's species and which 



I consider identical. 



Bell subhernispherical to half ovoid, very transparent, with firm walls; marginal tentacles I. 

 stout, rather stiff, and with evident terminal knobs, basal hull is prominent, each \\ iih a single black 

 ocellus ..n its outer central surface; manubrium usually long, though highlj contractile and distin- 

 guished by one or more rather sharp constrictions, usually one at the base and another about the 

 middle, suggesting the specific designation. Mouth simple or slightly lobed. 



Colors. — Body of manubrium bright green margined with red or pink; tentacular bulbs reddish 

 orange, terminal knobs bright reddish. 



Distribution. — Common at Woods Hole, rare at Newport I Fewkes). 



Dipurena conica A. Agassiz. 



1 >il> tin mt conica A. Agassiz, in 1. Agassiz's Contributions to the Natural History <>i' the United States, Vol. IV, 1862, p. :;n 



North American Acalephse, 1865, p. 181. 

 Sltibbcria conica Haeckel, Prodroraus Systems; Medusarum, is;;. No 16 

 Dipurena conica Haeckel, System der Medusen, 1879, p. 24. 



Bell conical t . hemispherical, with rather firm aboral thickening; marginal tentacles -1, of same 

 character as in preceding species; manubrium indistinguishable from preceding; month similar. 



< 'olors. — Indistinguishable from preceding. 



Distribution. — Buzzards Bay, Vineyard Sound, etc. 



Medusa; answering in every particular to Agassiz' s description have been taken constantly for main 

 years, but associated with individuals which as clearly correspond with the preceding; and, what is 

 more significant, these two forms graduate imperceptibly into each other in all essentials of shape, 

 structure, etc. It seems altogether probable, therefore, that we have here simply a varietal form, 

 which would hardly justify specific separation, and should probably he included under the above 



species. 



DIPURELLA Hargitt (1!>02). 



Resembling in some respects the preceding genus, these medusa' have marked differences in shape 

 of hell, form of manubrium, and certain aspects of the tentacles, demanding generic distinction. 



Dipurella clavata Hargitt. PI. I, fig. 3. 

 Dipurella clavata Hargitt, Biological Bulletin, v.. I. IV, 1902, p. 19. 



Bell rather high, subrectangular in profile with slight apical projection; sides of bell almost straight, 

 thin, flexible, and capable of marked contraction both in long and short diameters. Surface of the 

 exumbrella dotted rather promiscuously with clusters of nematocysts. Radial canals -I, rather wide 

 and simple. Tentacles 4, unequally developed in the type specimen. This difference would seem 

 t.. he due to immaturity, as is also indicated by the exumbrellar nematocysts. It will he noted from 

 a comparison of the figures of this medusa and Dipurena that there is more or 'less similarity in the 

 form and general aspects of the tentacles. Both are rather stout and rigid, both end in clavate knobs, 

 hoth have similar basal bulbs. On the other hand the knobs of Dipurella are of a heavier and more 

 clubdike character, and in addition there is about the median portion of each tentacle a ring of 

 nematocysts which are wholly peculiar to the latter species. The manubrium is sessile, rather short. 

 with large gastric basal portion; mouth simple or slightly lobed. 



Colors. — Chiefly restricted to the tentacles; terminal knobs with bright carmine-red center tinged 

 ivith delicate green; basal bulbs duller orange, red. or brown; ocelli black; manubrium tinged with 

 pale green. 



Distribution. — A single specimen taken in Great Harbor. Size small, 'J nun. in height by about 

 1.5 mm. in width. 



