ANTIKiMKDIS.K ST< iM( iT( i( 'A, DISSi i\KM \ . II.") 



medusa swims by the aid ot a rhythmical series ot wave-like contractions which travel one 

 after another up the very flexible sides ot the hell, from margin to apex. The efficiency ot 

 these movements is greatly enhanced In the cooperation of the powerful velum. 



The 4ully-developed medusa is unknown and it-is possible that this medusa may not be 

 Stomotoca. It can not be referred to any Turns known upon our coast, and the tact that the 

 2 long tentacles are of unequal length, one being considerably longer than the other, separates 

 it at once from any other known species of Sttjtnotrjici. At present we place it provisionally 

 in the genus Strjinotoca to which its hydroid appears to refer it. Were it not for the absence 

 ot ocelli upon the tentacle-bulbs I would be inclined to suspect that this medusa might prme 

 to he the young ot Turns pileato. 



(Stomotoca?) Perigonimus cidaritis Weismann. 



Pfrigottiniiis cidaritisi WUSMANN, 1885, Entstehung Sexualzellen bei Hyiimmciluscn, pp. 117, 218, taf. 12. figs. 10, 11. 



The stems of the hydroid are about 90 mm. high and arise thickly one by the side of the 

 other from a root-like hydrorhiza. The stems are often simple and unbranched, but tlu\ 

 commonly branch dichotombusly one or two times, the branches being set off at acute angles 

 one with another. The hydranths have a circlet ot about 20 tentacles. Perisarc thin and 

 yellowish. The medusa-buds are borne upon pedicels in a zone at the bases ot the hydranths. 

 When set free the medusa is spherical, with 4 marginal tentacles and 4 radial-canals. The 

 manubrium has 4 short, knobbed oral tentacles. The whole hydroid stock is invested with 

 a thin layer of slimy mud, leaving only the mouth-ends of the hydroids projecting, and some- 

 times even those are covered, leaving only the tentacle tips tree. 



Found at Naples, Italy. Medusa set tree in March. 



The sex-cells originate in the ectoderm ot the proximal part of the manubrium of the 

 medusa-bud and develop in their place of origin, becoming mature in the tree medusa. The 

 mature medusa has not been determined. 



Genus DISSONEMA Haeckel, 1870. 



l)ionrma, HAF.I KM, 1X7.), Svst. dcr Mrdusen, p. 126. MAYF.R, 1900, Bull. Mus. C'oinp. /.mil. .11 H.ir\.ir,l (.'iill'-i'r , \nl. ;-, 

 p. 44. BK;F.UHV, H. B., 1909, Bull. MiiM'um of Comp. Znol. ;it Harvanl Colli-iv. 



This genus was founded by Haeckel, \$~(), for Dissotit-itiii .\ii[>lii'n,-llii, of the- coast <>l 

 Australia. 



GENERIC CHARACTERS. 



Tiarinas with two hollow, diametrically opposite tentacles. The gonads extend from 

 the manubrium outward along the canals. Without marginal sense-clubs. Cirri aie some- 

 times present. With abaxial, ectodennal ocelli upon the bases ot the tentacles. 



Rigelow, 1408, finds that the adradial gonads begin to develop upon the sides of the 

 manubrium and that afterwards they extend outward over the radial-canals. The hollow 

 tentacles, abaxial ectodermal ocelli, rudimentary tentacle-bulbs, and hollow bell-apeK are 

 all characteristic of the Tiarinae., and it appears that this genus must be removed trom the 

 Thaumantiad;e, in which Haeckel placed it. 



J)is.friiii-niii bears the same relation to Stin<tt't,<i that .\<//;<//MM does to Bougainvillta. 

 The hydroid is unknown. 



Dissonema saphenella Haeckel. 



/>;\w,'M w<; niplifntlla, HAFI KKI, 1879, Svst. tier Mcduscn, p. 126, t:tf. 8, rl^. }. 



Bell pyriform, with thick, solid apex and thin, bulging sides. 6mm. high, 4 mm. uulc. 

 2 well-developed tentacles, several times as long as the bell-height. These tentacles have 

 large, swollen, conical basal bulbs. There are 2 rudimentary tenta'cle-bulbs yo apart trom 

 the long tentacles. There is an abaxial (ectodermal ?) "ocellus" ot large si/e upon each ot 

 the 4 tentacle-bulbs. There are no marginal clubs, cirri, or other appendages. 



The velum is well-developed and there are 4 straight, narrow radial-canals and a ring- 

 canal. The manubrium is cylindrical, half as long as the depth of the bell-cavity and pro- 

 vided with 4 short, crinkled lips. The 4 folded, spindle-shaped onads are developed upon 

 the middle three-fourths of the radial-canals. Color ( ?) Coast ot Australia. (See tig. ' 



