MAYER: MEDUS-E FROM THE TORTUGAS, FLORIDA. 47 



lated lips. The entoderm of the proboscis in some specimens is green, in 

 others pearly-white or yellowish. The entodermal pigment spots at the bases 

 of the tentacles are dark brown. 



Stages in Development. — The youngest medusa observed possessed a bell 

 1.5 mm. in diameter (see Figure 15). It had 4 simple radial canals, and 32 

 tentacles, 4 well developed and 28 rudimentary. The velum was prominent. 

 There were 4 lips to the proboscis, and as yet no peduncle. There was no 

 trace of the genital organs. In the next older stage (Figure 16), we find 16 

 radial canals, and 8 lips to the proboscis. As yet there is no peduncle and 

 no trace of the gonads, nor have the radial tubes grouped themselves into four 

 bundles as in the adult. 



This medusa was very common at the Tortugas in June, and ample oppor- 

 tunity for observing its transformation was afforded. It possesses the curious 

 habit of collapsing into an almost shapeless mass, in which condition it may 

 remain for several hours and then " straighten out " and swim about in ex- 

 cellent condition. 



Fewkes, 1883 (" On a Few Medusae from the Bermudas," Bull. Mus. Comp. 

 Zool., Vol. XI., No. 3, Figures 7, 7") has evidently figured the young of this 

 species under the name of " Larva of an unknown Tubularian." 



DYSCANNOTA. IIaeckel, 1879. 

 Dyscannota gemmifera. 



Fig. 17, Plate 8. 



WiUia ornata ? Brooks, W. K., 1880, American Naturalist, Vol. XIV. p. 670. 

 Willia ornata, Brooks, W. K., 1881, Studies Johns Hopkins Univ. Marine Lab., Vol. 



II. p. 144. 

 Willia gemmifera, Fewkes, J. W., 1882, Bull. Mus. Comp. Zool. at Harvard Coll., 



Vol. IX. p. 300, Fig. 24, PI. I. 



Specific Characters. — The bell is hemispherical, with a slight apical pro- 

 jection, and is 4 mm. in diameter. There are 12 long tentacles with well- 

 developed basal bulbs. Each tentacle ari.ses from the point of juncture of a 

 radial tube with the circular vessel. The velum is well developed. 4 radial 

 vessels arise from the proboscis, and each of these gives rise to two side 

 branches, so that 12 radial tubes reach the circular vessel. In addition to these 

 12, very slender tubes branch off at right angles to the circular vessel and end 

 blindly in the gelatinous substance of the bell. These tubes alternate with 

 the 12 radial tubes and tentacles. Each one terminates under a cluster of 

 nematocysts upon the outer surface of the bell. The proboscis is long and 

 slender, and reaches about three quarters of the distance from the apex of the 

 bell cavity to the velar opening. It is provided ■with 4 slightly recurved and 

 fimbricated lips. This species is remarkable in that a stolon arises from each 



