514 



MEDUSAE OF THE WORLD. 



bell-margin. In Chiropsalmus, on the other hand, each of the 4 pedalia gives rise to side 

 branches which bear tentacles. Moreover, in Tripedalia there are no subumbrella, hernia- 

 like, gastric diverticula as in Chiropsalmus. 



Tripedalia cystophora Conant. 



Tripedalia cystophora, CONANT, 1897, Johns Hopkins Univ. Circulars, No. 132, p. 9, fig. 9; 1898, Mem. Johns Hopkins Univ. 

 Biol. Lab., vol. 4, No. I, pp. 5, 22; figs. 17-30, plates I, 2, 5, 7, figs. 44, 45, 53-56, 68, 71. 



Bell cubical, with edges slightly rounded; 12 mm. high, and of about 15 mm. wide. 

 There are 4 interradial groups of pedalia, each group consisting of 3 distinct, separate pedalia, 

 each one of which arises from the bell-margin and gives rise to a single tentacle. The pedalia 



are flattened and resemble a slender knife-blade, and 

 are about half as long as the bell-height. The 12 

 tentacles are each about 2.5 times as long as the 

 pedalia. 4 sense-clubs are situated in niches at about 

 one-fifth or one-fourth the height of bell above mar- 

 gin. Each sense-club has 2 large, median and 4 small, 

 lateral eyes and a terminal lithocyst. The median 

 eyes have doubly convex lenses. Velarium about 

 one-sixth as broad as bell-diameter. There are 24 

 simple, unforked velar canals, 6 in each quadrant. 

 These velar canals are triangular in outline, and the 

 8 adjacent to the 4 frenulae are only half as wide as 

 the others. Stomach wide and shallow, butthethroat- 

 tube is lono- and extends downward in some cases to 



O 



bell-margin; cruciform in cross-section, with 4 well- 

 developed, oral lobes in the radii of the sense-organs. 

 There are 15 to 21 organs, resembling lithocysts, in 

 the gelatinous walls of the manubnum; each con- 

 sists of a round or oval sac lined with ciliated cells 

 which keep in motion and bear up an irregular, 



FIG. 170. Tnhedalia cystophora* i IT > TI 



coarsely granulated concretion. These organs are 



scattered irregularly through the gelatinous substance and are probably of entodermal origin. 

 The small, tapering, gastric cirri are brush-shaped and spring from 4 short stalks in the inter- 

 radial corners of the stomach. There are 4 wide, perradially situated, gastrovascular 

 pouches in the umbrella, which are separated by 4 interradial septa; but these septa are 

 incomplete in the regions of the pedalia, and thus the 4 stomach-pouches are placed in com- 

 munication one with another, as in other Charybdeidae. The gonads are 8 leaf-like sheets 

 attached to the sides of the 4 interradial septa and projecting out into the 4 perradial 

 stomach-pouches. The medusa is light yellowish-brown, the gonads being of the same color. 



Figure 330 shows a mature female, 4 times natural size, drawn from nature, by the author. 

 In order to illustrate their shape, the lips are shown twisted 45 from their natural position. 



This species is found in Kingston Harbor, Jamaica, in great abundance during the sum- 

 mer among the mangrove roots ot the islands in a shallow, muddy lagoon on the western side 

 of the harbor, north of Port Henderson. It disappears in winter. 



The dimensions of the mature specimen here figured are as follows: Bell 12 high, 15 

 mm. wide. Pedalia 5 mm. long, 2.1 mm. wide. Rhopalia 2.25 mm. above velarium margin. 

 Stomach 5.5 mm. wide, j mm. long. The gonads were mature and the gastrovascular space 

 filled with swimming planulae. This medusa was captured on May 24, 1909. 



Conant succeeded in obtaining females having embryos within their gastrovascular 

 pouches. The embryos were thrown out into the water as free-swimming planulse, which 

 settled down on the bottom and sides of the aquarium in a day or two and quickly developed 

 into small Scyphostomae with mouth and typically with 4 tentacles and 4 taeniolae, although 

 3 and 5 tentacled specimens were not uncommon. In this condition they lived for 3 weeks 

 without essential change. I find that many, but not all of the planulse, are besprinkled with 

 dark brown pigment-spots which are scattered over the ectoderm of the narrow posterior end 

 of the larva. 



