46 MEDUSAE OF THE WORLD. 



Dicodonium cornutum Haeckel. 



Dicodonium cornutum, HAECKEL, 1879, Syst. der Medusen, p. 27, taf. I, fig. 6. 



Haeckel found this species at Tur, near Sinai, in the Red Sea. See tabular description of 

 medusae of Dicodonium. It has no ectodermal ocelli upon the bulbs of the 2 large tentacles. 



Haeckel presents a beautiful figure of the medusa, drawn 

 from life. 



Dicodonium dissonema Haeckel. 

 Dicodonium dissonema, HAECKEL, 1879, Syst. der Medusen, p. 27. 



Haeckel describes this from a preserved specimen from 

 the coast of Australia. See tabular description of the 

 medusae of Dicodonium. 



"Dicodonium ocellatum." 



FIG. 12. Dicodonium cornutum, after Sarsia ocellata, BUSCH, 1851, Beobach. wirbellos. Seeth., p. 16, taf. 2, figs. 1-3. 

 Haeckel, 1879. Dinema ocellatum, HAECKEL, 1879, Syst. der Medusen, p. 29. 



This medusa is described by Busch from Trieste, Adriatic, and it is probably an abnormal 

 Sarsia with only 2 of its 4 marginal tentacles developed. See tabular description of the medusae 

 of Dicodonium. 



Dicodonium floridana Mayer. 

 Plate 2, fig. 5. 



Bell about 4 mm. high and 3 mm. wide, with thin, uniform, vertical walls and a slight 

 apical projection. There are 2 equally-developed, diametrically opposed tentacles, each 

 about three-fourths as long as the bell-height. Near the outer end of each of these tentacles 

 there is a large, knob-like, swollen region, which terminates in a thin, tapering, nematocyst- 

 bearing lash. The knob-shaped swelling is hollow and its cavity is connected with the general 

 gastrovascular system of the medusa by means of a slender tube which extends through 

 the entodermal core of the tentacle. The basal bulbs of the tentacles are not large, and there 

 are no ocelli. 



In addition to the 2 long tentacles, there are 2 small, tapering, rudimentary tentacle- 

 bulbs 90 from the large tentacles. The velum is well developed. There are 4 straight, 

 narrow radial-canals and a simple, narrow circular canal. The manubrium is flask-shaped, 

 being narrower at its base than at its middle point. The mouth projects slightly beyond the 

 velar opening, and is a simple, round opening at the extremity of a long, tapering neck. The 

 gonads are within the wall of the manubrium. The entoderm of the stomach is yellow, and 

 that of the distal bulbs of the tentacles yellow flecked with orange. The entoderm of the basal 

 bulbs of the tentacles is also tinged with yellow. 



This medusa is occasionally found at Tortugas, Florida, in June. Occasionally a speci- 

 men is taken in which the normally rudimentary tentacles have developed so as to be nearly 

 as long as the pair of large tentacles, thus illustrating the imperfect line of separation between 

 Dicodonium and Sarsia. 



Dicodonium jeffersoni Mayer. 



Plate 2, fig. 4; plate 3, fig. I. 

 Dinema jeflersoni, MAYER, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 30, plate 37, fig. 126. 



The bell is dome-shaped, higher than a hemisphere, and about 0.75 mm. high. The 

 exumbrella surface is sparsely sprinkled with nematocysts. There are 2 short marginal 

 tentacles, and 2 rudimentary tentacle-bulbs. The tentacles are radially situated, and are 

 covered with numerous small wart-like clusters of nematocysts. There are 4 ectodermal 

 ocelli, I upon the outer side of each of the 4 tentacle-bulbs. The velum is well developed. 

 There are 4 straight, narrow radial-canals and a narrow circular vessel. The manubrium 

 is about as long as the depth of the bell-cavity. It is simple, cylindrical, and tube-like, and 

 the mouth is a round opening at the extremity of a short, cylindrical neck. A simple canal 



