44 Bulletin, Vanderbilt Marine Museum, Vol. IV 



the mouth-arm disk. Besides these filaments there are many short, 

 clavate, nematocyst-bearing vesicles scattered among the mouths. The 

 mouths are located on the oral, principally on the primary and sec- 

 ondary branches of the arms and in less abundance on the oral sides 

 of the eight basal trunks of the arms. In the adult medusa there are 

 no mouths at the center of the mouth-arm disk. Very numerous fine 

 waving tentacles fringe the mouths. There are four small, deep, oval, 

 interradial, subgenital pits, and four separate invaginated genital 

 sacs. The central stomach is cruciform ; the four sac-like gonads some- 

 what encroaching upon it at the interradial sides. The axial ducts of 

 the eight oral arms open into the central stomach at the four principal 

 radii. Also arising from the central stomach are twice as many radial 

 vessels as there are marginal sense organs; every other vessel extends 

 to a sense organ, the remainder going to intermediate parts of the rim. 

 All of these vessels communicate with one another by means of anas- 

 tomosing branches, but this species lacks a well-defined circular vessel, 

 such as is found in Cassiopea ornata. 



References : Cassiopea xamachana H. B. Bigelow, Zoolog. Anz. Bd. 

 15, p. 212, 1892 ; Johns Hopkins Univ. Circ, vol. 11, p. 17, p. 84, 

 1892 ; Jrn. Inst. Jamaica, vol. I, p. 301, 1 pi., 1893 ; Mem. Boston 

 Soc. Nat. Hist., vol. V, no. 6, p. 191, figs. A to L, pis. 31-38, 

 66 figs., 1900. — Perkins, Yearbook, Carnegie Inst. Washington, 

 No. 4, p. 118, 1904 ; Publ. 102, Carnegie Inst. Wash., p. 150, pi. 4, 

 1908. — Mayer, A. G., Yrbk., Carnegie Inst. Wash., no. 4, p. 117, 

 1906; Publ., Carnegie Inst. Wash., no. 47, pp. 1-62,1906 (discusses 

 rhythmical pulsation) ; Yrbk., Carnegie Inst. Wash., no. 6, p. 121, 

 1907 ; ibid, no. 7, p. 123, 1908. — Maas, Scyphomedusen der Siboga 

 Exped., Mon. 11, p. 40, 1903. — Stockard, Yrbk., Carnegie Inst. 

 Wash., no. 6, p. 119, 1907 (discusses regeneration) ; ibid, no. 7, 

 p. 130, 1908 ; Papers Tortugas Labr. Carnegie Inst. Wash., vol. 2, 

 p. 61, figs. 1-29, 1909 ; Journ. Exper. Zool., vol. 6, p. 433, 8 figs., 

 1909. — Zeleny, C, Jrn. Exper. Zool., vol. 5, p. 265, 4 text figs., 

 1907 (discusses regeneration). — Dahlgren and Kepner, Text 

 Book of Principles of Animal Histology, p. 88, fig. 85, 1908 (dis- 

 cusses histology of the muscles). — Mayer, A. G., Papers Tortugas 

 Labr. Carnegie Inst, of Washington, Publ. 102, p. 113, 1908 (dis- 

 cusses cause of rhythmical pulsation) ; Popular Science Monthly, 

 vol. 73, pp. 481-87, 4 figs., 1908; Kept. Seventh International 

 Zool. Congress, 4 pp. — Harvey, Yrbk., Carnegie Inst. Wash., no. 

 8, p. 120, 1909. 



