710 MEDUSAE OF THE WORLD. 



Stomolophus meleagris L. Agassiz. 

 Plates 75 and 76, figs. 1-3. 



Cep]iea rhizosloma, GIBBES, 1847, (non Lamarck) Fauna of South Carolina. 



Stotnoloplius meleagris, AGASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, pp. 138, 151; Ibid., 1860, vol. 3, plate 14, figs. 1-8. 



AGASSIZ, A., 1865, North Amer. Acalephx, p. 40. 



Slonwlophus meleagris+S. agaricus ?, HAECKEL, E., 1880, Syst. der Medusen, p. 599. 

 Stomolophus chunii, VANHOFFEN, E., 1888, Bibliotheca Zoologica, Bj. i, Heft. 3, pp. 31, 42, taf. 3, fign. 4, 5; taf. 4, fig. I. 



TRINCI, G., 1906, Ajinuar Mus. Zool. Napoli, ser. 2, vol. 2, No. 9, pp. 1-4. 



Bell about 180 mm. in diameter, half-egg-shaped, higher than a hemisphere, the gelatinous 

 substance thick and rigid; no marginal tentacles; 8 marginal sense-organs, 4 radial and 4 

 interradial. Each sense-club is deeply set within a niche between the ocular lappets and is 

 protected above by a partial web between the lappets. Sense-club hollow and spindle-shaped, 

 terminating in a knob-like end which contains an entodermal mass of deeply pigmented 

 concretions. A deep, j-sided, furrowed pit projects inward from the surface of the exumbrella 

 just above the base of each sense-club (see [c] fig. 2'", plate 75). About 128 marginal lappets, 

 16 in each octant, those flanking the sense-organs being about 3 times as long as the others. 

 The velar lappets have rounded edges, but the ocular lappets are longer and sharp-pointed. 



A rigid, thick-walled mouth-tube, or manubrium, projects downward from the center 

 of the subumbrella and extends 40 to 50 mm. beyond level of bell-margin. This manubrium- 

 hke tube is formed by the lateral coalescence of the 8 adradial mouth-arms, which are fused 

 along their adjacent sides, their extreme ends only being free. These free ends of the mouth- 

 arms bifurcate and flare outward at lower end of manubrium. A deep groove, or gutter, 

 extends along the ventral side of each of the 8 mouth-arms and branches dichotomously twice 

 and extends outward over the lower sides of the 16 free ends of, the mouth-arms. The free 

 edges of this branching groove are complexly branched and folded and are lined by a row of 

 numerous small knobbed tentacles', which move constantly in such manner as to drive food 

 particles into the mouth-grooves. In addition to the central mouth, there are numerous slit- 

 like lateral mouths which are situated upon 16 knife-blade shaped scapulets attached to the 

 upper part of, and occupying more than half of the length of, the manubrium. The free edges 

 of these lateral mouths are complexly crenulated and lined with small, incessantly waving 

 tentacles exactly as are the mouth-grooves at the free extremity of the manubrium (fig. 2, 

 plate 76). The 8 main mouth-grooves of the manubrium lead into a 4-cornered, central 

 oesophagus which extends upward into the wide, central stomach. 16 lateral branches, 4 

 from each side of this four-cornered oesophagus, extend outward to the slit-like mouths in 

 the 16 scapulets. These radiating tubes arise from the oesophagus near the level of the 

 upper parts of the scapulets. The central stomach is wide and lenticular, and occupies the 

 midst of the umbrella. It gives rise peripherally to 16 radial-canals which in their outer 

 halves give off many side branches which in turn form an anastomosing network placing all 

 of the radial-canals in connection one with another, as in the genus Rhizostoma. No ring- 

 canal. 



There are 4 deep, cylindrical subgenital pits, and a blunt papilla is found on the sub- 

 umbrella surface just beyond the opening of each genital ostium. The gonads are found in 

 4 folded regions in the wall of the subumbrella at the bottom of the subgenital pits. There 

 are 16 semi-elliptical areas of circular muscles in the subumbrella, 2 between each succes- 

 sive pair of sense-organs. Alternating with the circular-muscle areas there are 16 narrow, 

 triangular strands of weakly developed radial-muscle-fibers, the broad end of each triangle 

 abutting against the side of the manubrium, and the narrow, pointed end being directed 

 outward. 8 of these occupy the radii of the marginal sense-organs and 8 are intermediate in 

 position. The bell-margin pulsates incessantly with remarkable strength and rapidity. 



The gelatinous substance of the bell is of a milky bluish or yellowish color and the ento- 

 dermal parts are dull yellow. The surface of the exumbrella is reticulated with brown pigment 

 which is especially dense near the margin. There are numerous white or yellowish spots in this 

 brown marginal zone. The mouth-frills are brownish-pink. 



young medusa. I have captured an immature medusa of this species in which the bell 

 was 3 mm. in diameter and the entire animal 5 mm. in length (fig. 3, plate 75). The bell 

 was flatter than a hemisphere and the surface of the exumbrella was covered with wart-like 

 clusters of nematocysts, among which there were numerous, brown-colored pigment cells. 



