I.I I'l' 'MUM > I! Diri.KI IdisnM v. 



Harbor, Ireland, the number of radial-canals arising fiom the periphery of tin stomach 

 ranged troni 5 to |H, 43 of the medusae hav ing .y canals. Canals exceedingU irregular in position 

 and in mode of branching, so that it is impossible to define a normal t\pe. but rhe\ appear nor- 

 mally to connect with the circular \essel. The Bounds are developed upon radial-canals adja- 

 cent to the stomach and may be upon all or on onl) a few of the canals. Tin \ van in number 

 from i to 12, and 5 is the most frequent number. The females are in excess of the males in 

 the proportion of about 4 to 3. The ova remain attached to the ovary until the planula stae 

 is reached. They were partially reared by the Misses Delap, and developed into hydioids 

 apparently belonging to the genus Cuspidella isee Browne. 1900, p. 696). 



The gonads, stomach, and tentacle-bulbs are said to be brownish (Haeckel. iS; 



The changes which the medusa undergoes in its growth are unkno\\n, but Browne be- 

 lieves that the stomach is primarily regular in shape and that it becomes irregularly elongated 

 into lobes by development of the radial-canals. 



118. 



Fu;. 117. Dipleurosoma ("amphitheetum"'), after H.irckcl, 1879. 

 l'i'.. iiS. -Dipleurosoma pticificti, atlt-r N I . in 



\lu -rum Cornp. Znol. at Harvard C<>llri;<.. 



D. tvpii-iuii of the Ninth Atlantic may prove to be identical with /). [>iii'i/ii-a from Tahiti, 

 South Pacific. The only distinctions between the North Atlantic and the tropical Pacific 

 species are their wide geographical separation and the presence of' maiginal clubs in I). 

 piififiin. Dtpleurosoma tvp/fiiiii has been taken ott the northern coasts of Europe and <>rl 

 Newfoundland. 



Dipleurosoma pacifica Agassiz and Mayer. 



Diplcurosoma pacifica, Ac, AS si z A., AND MAYI K, 1902. Me in. Muv. Com p. /.""I . at H.n uir^l (.'"II ., \"\ . ;l>. p. i 48, plate j, figs. 13, 14. 



Bell very flat, about j times as broad as high, 2} mm. in diameter. Surface of exumbrella 

 reticulated by a regular system of hexagonal elevations bounded b\ shallow turn>\\s. About 

 100 short tentacles with narrow, bulbular bases. Kntodermal core of these tentacles is solid 

 and composed of chordate cells. At the bases of most tentacles upon the lower (subumbrella) 

 side, there is a single black ocellus. Slender, club-shaped, sensory bodies aie scattered at fre- 

 quent and irregular intervals between the tentacles. Entodermal cores of these bodies air solid 

 and very similar to those of the tentacles. No concretions. Velum narrow. <> radial-canals 

 arise in groups of 3 from diametrically opposite sides of the stomach. In the single specimen 

 examined, 2 of these canals bifurcate, and 8 canals thus reach the circular vessel. The <;onads 

 are linear and occupy the middle regions of the S canals. Their surfaces are slighrlv papillate 

 and the ova stand out as hemispherical protuberances. Stomach elongated in the direction of 

 the two opposed groups of radial-canals. Manubrium very short, 6 small, slightly folded lips. 



Tentacle-bulbs, genital organs, and manubrium milky white, all other parts of the medusa 

 being transparent. A single specimen was obtained in a surface haul about 50 miles ninth of 

 Tahiti. Smith Pacific. 



