RHIZOSTOM.E STO.MOLOPH r S. 711 



There were 8 marginal sense-organs and 48 marginal lappets (fig. i, plate 76). The lappets 

 flanking the sense-organs were about twice as long as the others. The ocular lappets were, 

 however, simple while the others were bifurcated and evidently in process of division. The 

 central mouth was situated at the extremity of a long 4-cornered proboscis which possessed 4 

 bifurcated lips. The free edges of these lips were lined by a row of short, slender, knobbed 

 tentacles which maintained a constant motion. In addition to the principal or terminal mouth 

 there were 8 small, tube-like, lateral mouths arranged in 4 pairs, the beginnings of the scapulets. 

 These mouths arose from the sides of the manubrium near its base and were interradial in 

 position (/. <., 90 from the radii of the 4 principal lips), and in addition to these lateral mouths 

 there were 4 pans of hernia-like protections upon the surface of the manubrium. These pro- 

 jections alternated in position with the already functional, lateral mouths, and would no doubt 

 soon ha\e broken through and formed another set of such mouths (fig. i, plate 76). The 

 functional mouths were each surrounded by 8 tentacles which w r ere similar in structure to the 

 tentacles lining the free edges of the principal mouth. 



The medusa was quite transparent except for a trace of brown pigment in the ectoderm 

 of the exumbrella and the dark-red pigment of the sense-organs. 



I found it in Charleston Harbor, South Carolina, on September 9, 1898. 



The resemblance between this young rhizostomous medusa and the adult condition in 

 the Semaeostomeae is very striking. The terminal mouth was used, indeed, for the capture of 

 food, an operation which was facilitated not only by the flexibility of the lips but also by the 

 incessant motion of the tentacles. 



This species is very common along the sandy coasts of North and South Carolina and 

 Georgia. In April, 1910, mature medusae were abundant at Tortugas, Florida. It does not 

 extend north of the mouth of Chesapeake Bay. It is found along the northern coast of South 

 America, and at many places in the Gulf of Mexico, and I believe it to be identical with .V. 

 fliiinii Vanhiiffen, from the Bay of Panama on the Pacific side of the Isthmus. It often occurs 

 in vast swarms, occupying an area which is sometimes over 100 miles in length. Mature 

 individuals are abundant in winter and spring off the coast from Florida to South Carolina. 

 It is not often seen in brackish harbors, but is practically confined to pure ocean water off 

 the coast. At most it enters only the mouths of harbors. 



I can see no difference between 5. chunn Vanhoffen and S. mcleagns. S. cliunii is 

 described as being only 90 mm. wide and with only 112 marginal lappets. In all respects it 

 resembles a half-grown S. meleagris. Indeed, Trinci, 1906, records S. chunii from the Gulf 

 of Paria between Trinidad and Venezuela, Atlantic coast of South America, and it appears, 

 therefore, that "S. chunn" must occur on both Atlantic and Pacific sides of the Isthmus of 

 Panama. It is probable that the medusa has remained unchanged since the closure of the 

 Isthmus in Mesozoic times. 



Haeckel's Brachiolophus collans is only a younger stage of the same medusa with a bell 

 80 mm. wide and with 80 marginal lappets. It is described from the Galapagos Islands. 



Stomolophus meleagris var. fritillaria. 



Stomotoptius friiillaria, HAECKKL, 1880, Syst. der Medusen, p. 598, taf. 35, fign. 1-9. VON LENDENFELD, 1884, Proc. Linneao 

 Soc. New South Wales, vol. 9, p. 292. VANHOFFEN, 1888, Bibliotheca Zoologica, BJ. i, Heft, j, pp. 31, 42. 



This form appears to be smaller than S. meleagris, the bell being only about 80 mm. in 

 diameter and (>o mm. in height. The marginal lappets are more numerous, being 208 in 

 number. The "manubrium" or fused tube of mouth-arms extends only about one-fourth 

 the bell-height beyond the level of the margin, instead of about one-third the bell-height, as 

 in .S 1 . iiii-lt-/i^ris. This medusa is found at Suranim on the Atlantic coast of South America. 

 Color(?) 



The only valid distinctions between this medusa and S. meleagris are in its large number of 

 marginal lappets, and in the cleft in the middle of each octant of velar lappets. Also the 16 

 scapulets are hidden well up under the bell instead of extending down to about the level of 

 the bell-margin. It may be regarded as a southern variety of S. meleagris. Haeckel describes 

 it from 3 alcoholic specimens in the Copenhagen museum. 



