RHIZOSTOMiE — COTYLORHIZA. 659 



is a single suhgenital porticus. The appendages upon the mouth-arms are mounted upon 

 pedunculated filaments. There are 8 marginal sense-organs and numerous radial-canals 

 which anastomose laterally without any definite ring-canal in the adult. The sense-cluhs 

 have no ocelli and no exumbrella sensory pit. There is a unitary peripheral zone of circular 

 muscles and an inner zone of radial-muscles in the subumbrella. The exumbrella is smooth 

 and without an aboral "sucker-like" depression, but with a prominent central dome without 

 wart-shaped elevations upon it. 



This genus is sharply separated from Cassiopea, with which it has often been confused, 

 by its single, unitary, subgenital porticus, its relatively simple bifurcated mouth-arms, and by 

 having constantly 8 instead of an indefinite number of marginal sense-organs. Also there is no 

 aboral "sucker" upon the exumbrella, such as is commonly seen in Cassiopra. 



Cotylorhiza tuberculata L. Agassiz. 



Plate 73, fig. 2. 



Medusa tiiberculaln, Macri, G., 1778, Osservazioni Int. Polmonc Marino, p. 20.— Linne, (Gmelin), 17S8, Systcma Nalurac, 

 Ed. 13, Pars. 6, p. 3155. 



Medusa tuber, Macri, S., 1825, .'\tti Rcale Acad. Sci. Napoli, vol. 2, Parte 2, p. 74, tav. 4, figs. 1, 2. 



Cephea polychroma, Pkron f.t Lesueur, 1809, Annal. du Mus. Hist. Nat. Paris, tome 14, p. 361. — Lamar( pc, 1S16, Hist. Anim. 

 sans Vert., tome 2, p. 516. 



Cassiopea borhonica, Delle Chiaje, 1823, Memorie suUa storia e notomia degli animali senza vertcbre, Napoli, Mem. 3, p. 75, 

 tav. 3, 4, figs. 1-6; 1841, Animali senza vert., Napoli, tome 7, tav. 140-141. — Kowalf.vsky, 1873, Mem. Imp. Soc. Friends 

 of N.it. Hist., Moscow, vol. 10, part 2, p. 3, plate 2 (Russian).— Du Plessis, 1881, Bull. Soc. Vaud. Sci. Nat., vol. 17, 

 No. 86, p. 633, plate 31 (development of egg-scyphostoma).— De Merejicowsky, 1882, Arcliiv. Zool. Exper. et Generale, 

 tome 10, p.577,planche 29B, figs. 14-20 (development of spermatozoa). — Claus, 1883, Arbeit. Zool. Inst. Wien, Bd. 5, p. 169, 

 2 taf., fign. l-ll (development of the ephyra); 1883, Organisation und Entwick. der Medusen, pp. 43, 53, taf. 11;, fign. 

 106-1 1 1 (ephyra); 1890, .Arbeit. Zool. Inst. Wien, Bd. 9, p. 85, taf. 4-6; 1890, Verliandl. Zool. Botan. Gesejl. Wien, IJd. 40, 

 pp. 54-55 (development of the scyphobtoma larva); 1892, Arbeit. Zool. Inst. Wien., Bd. 10, p. 1 (scyphostoma). — Graeffe, 

 1884, Arbeit. Zool. Inst. W'ien, Bd. 5, p. 343 (seasonal distribution). — Keller, 1S84, Recueil Zool. Suisse, tome 1, p. 403 

 (breeding habits of the medusa, and nature of the "yellow cells"). — Vanhuffen, 1SS8, Bibliotheca Zoologica, Bd. 1, Heft 3, 

 pp. 27, 40 (in the Red Sea). — Hesse, 1895, Zeit. fur wissen. Zool., Bd. 60, p. 441, taf. 21, fign. 17-19; taf. 22, fign. 27, 28 

 (nervous system of the subumbrella). — Bigelow, R. P., 1900, Mem. Boston Soc. Nat. Hist., vol. 5, No. 6, p. 209. — Hein, 

 1902, Zool. Anzeiger, Bd.25, p.637; 1902, Zeit. fiir wissen. Zool., Bd. 73, p. 302, taf. 20, 21 (development of the gastrula). — 

 Bethe, 1903, .MIgemeine Anat. und Physiol. Nervensystem, pp. 410, 414, 448, etc., fig. 83, 84, 88, 91, etc. (physiology of 

 the nervous system and of pulsation). — Maas, 1904, Result. Camp. Sci. Prince de Monaco, fasc. 28, p. 58, planche 2, 

 figs. 16-19; P'^'^ '>> fi?' 47> '9°3> Scyphomedusen der Siboga Exped., Monog. 11, p. 32, taf. S, fign. 69,70. — Boivifr, 

 1907, Bull. Instit. Oceanograph, Prince de Monoco, No. 93. 



( .^) Cassiopea coro!lifora+ C. canariensis, TiLESuis, 1829, Nova .Acta. phys. med. N. C, tome 15, pp. 265, 285, tab. 73. 



Cephea tuberciilatu, Eschscholtz, 1S29, Syst. der Acal., p. 56. 



Cephea wageneti, Will, 1884, Hnrs Tergestina;, p. 58. — BuscH, 1851, Anat. Entwickl. wirbell. Sccth., p. 30, taf. 2, 3.— Fran rzius, 

 1852, Zeit. fiir wissen. Zool., Bd. 4, p. 118, taf. 8, fign. 1-4 (siphostoma larva). 



Cassiopea borbonica, Gegenbaur, 1854, Generationswechscl Medusen, p. 2, taf. 2, fign. 32-35. 



Cotylorhiza tuberculata, AoAssiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 158. — Hamann, 1881, Jena. Zeit. fur Narurwissen, 

 Bd. 15, p. 254, taf. 9, fign. 8, 9; taf. 10, fign. 19-23, 34, 35; taf. 11, fign. 24-28 (structure of the mouth-arms). 



Cotylorhiza tuberculata, and C. ambulacrata (?) Haeckel, 1880, Syst. der Medusen, pp. 610, 611. 



Cotylorhiza borbonica, Gotte, 1885, Zool. Anzeiger, Bd. 8, p. 554; 1887, Abhandl. Entwick. der Thicre, Heft. 4, Leipzig, 79 pp.; 

 1893, Zeit. fiir wissen. Zool., Bd. 55, p. 645, taf. 28, 29 (embryology). 



Bell usually not more than 150 to 170 mm. in diameter, though according to Will it may 

 become 300 mm. wide. The dimensions of a large medusa found at Naples on December 28, 

 1907, were as follows: Hell 168 mm. wide, arm-disk 88 mm. wide, each mouth-arm 46 mm. 

 long and 54 mm. thick (dorso-vcntrally). The gelatinous substance is very rigid. The exum- 

 brella surface is smooth and without wart-like projections. 



The center of the exumbrella is occupied by a smooth, elevated dome, somewhat flatter 

 than a hemisphere and about as wide as radius of disk. Around the outer edge ot this dome 

 is a depressed region forming a gutter-like ring, somewhat lower than the parts of the bell 

 nearer the margin. There are 8 marginal sense-organs, which lack an exumbrella sensory 

 pit and have no ocelli. The sense-club has a very large, bag-like ventral bulb and contains 

 a terminal mass of orange-colored entodermal concretions. 



The marginal sense-organs are flanked by 16 short, blunt, oval rhopalar lappets. There 

 are typically 10 velar lappets in each octant, the middle 6 of which are sometimes, but not 

 always, cleft. The outer edges of these lappets are subrectangular with bluntly-rounded 

 angles. The primary clefts between the lappets are fully twice as long as the secondary clefts 

 of the 6 middle lappets; but all the clefts are bridged over by a web of subumbrella tissue, 

 so that they are not complete cuts, but mere grooves upon the exumbrella. The 16 velar 



