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AGASSIZ AND MAYER: DACTYLOMETRA. 
Dactylometra lactea L. Agassiz. 
Plates XII. and XIIL, and Fig. 10, Plate VII. 
Chrysaora lactea F. Eschscholtz, 1829; Syst. der Acal., p. 81, Taf. VII. Fig. 3. 
Dactylometra lactea L. Agassiz, 1862; Cont. Nat. Hist. of U. S., Vol. IV. pp. 
125, 126, and 166. 
Dactylometra lactea E. Haeckel, 1879; Das Syst. der Medusen, p. 517. 
Dactylometra lactea R. von Lendenfeld, 1884; Proc. Linnean Soc. New South 
Wales, Vol. IX. p. 271. 
Dactylometra lactea is the type species of the genus Dactylometra, 
which was established by L. Agassiz.! 
We shall confine ourselves to describing the differences which exist be- 
tween this species and its near ally D. quinquecirra. Figure 35, Plate 
XII., shows a young Dactylometra lactea in the stage where there are 
but four lappets, and five tentacles between each successive pair of sense 
organs. In the mature individual (Fig. 36, Plate XIII), on the other 
hand, there are six lappets and five tentacles between cach two sense 
organs. The tentacles of the mature individuals arise from the notches 
between the lappets. The primary tentacles when expanded may stretch 
out to a length of from two to three times the diameter of the bell. The 
secondary tentacles, however, are only about one half, and the tertiary 
about one quarter, as long as the primary ones. 
The general color of the medusa is a milky white ; and the bell is 
sprinkled over with light ochre-yellow spots, which are clustered thickly 
about the aboral pole. The genital organs are slightly yellowish, and 
a faint purplish iridescence is seen playing over the palps. The sense 
organs are of a brilliant white. A view of one of these sense organs as 
seen from the under side of the bell is given in Figure 10, Plate VII. 
Our figures were drawn from life, from specimens obtained in Havana 
harbor, Cuba, on February 22, 1893, while on the expedition to the 
Bahamas in the yacht “Wild Duck.” 
It is probable that this medusa is the species found by Eschscholtz in 
the Bay of Rio Janeiro, Brazil. 
The habits of this medusa are remarkable for their extreme regularity ; 
during the morning hours not one of them is to be found, while at about 
four o’elock in the afternoon they suddenly appear in large numbers, 
and remain swimming near the surface until long after nightfall. One 
1 Cont. Nat. Hist. of U. S., 1862, Vol. IV. p. 125. 
