LEPTOMEDUSiE PSEUDOCLYTIA, GASTROBLASTA. 279 



dant at Tortugas. It may be distinguished, however, by its color and the position of its 

 gonads upon the radial-canals, so that abnormal 4-rayed specimens of P. pentata can be dis- 

 tinguished from the normal Clytia folleata. 



Believing that P. pentata may be a successful mutation from some Clytia, in 1899 I carried 

 out a study of the variations of 1,000 specimens. The following is a summary of the results: 

 Among 1,000 specimens of P. pentata, 703 were normal and had 5 radial-canals and 5 lips, 72 

 apart, while 297 were abnormal. Of the abnormal medusae 151, or fully half, were radially 

 symmetrical. Medusae which are not radially symmetrical are very apt to be bilaterally 

 symmetrical. Normal 5-rayed medusae are more apt to be fertile and produce more ova than 

 do abnormal medusae, and thus the abnormal forms are produced at a disadvantage. The 

 commonest aberration is to display 4 radial-canals or 4 lips, or both, thus apparently reverting 

 to the ancestral type. The radial-canals ranged from 2 to 8, and the lips from 1 to 7. The 

 correlation in number between the radial-canals and the lips becomes less and less perfect as 

 we depart from the normal condition of 5 canals and 5 lips. 4 monstrous medusae with 2 man- 

 ubria, recalling the condition normal in Gastroblasta, were observed. Upon its reappear- 

 ance in 1909 the medusae were still highly variable. 



Pseudoclytia gardineri Browne. 



Pseudoclytia gardineri, Browne, 1904, Fauna and Geog. Maldive and Laccadive Archipelagoes, vol. 2, p. 731 , plate 55, figs. 1-3. 



Bell 5 mm. wide; gelatinous substance quite thin. About 13 to 14 tentacles about as 

 long as bell-radius and with globular basal bulbs. Rudimentary tentacle-bulbs somewhat 

 more numerous than tentacles and irregularly spaced, showing a tendency to cluster in one 

 quadrant where there are 6 bulbs, 3 on each side of a tentacle. There are 2 or 3 small litho- 

 cysts between each successive pair of tentacles; about 32 lithocysts in all. 5 radial-canals 

 somewhat irregularly spaced; 4ofthem are about 90 apart, and the fifth bisects the space 

 between two of the canals. Stomach small, without peduncle, and with 4 or 5 short lips. A 

 small gonad at the middle of each radial-canal. Maldive Islands, Indian Ocean; Milan- 

 dumadulu Atoll. Only 2 specimens found. It is possibly an abnormal Phialidium. 



Genus GASTROBLASTA Keller, 1883. 



Gastroblasta, Keller, 1883, Zeit. fur wissen. Zool., Bd. 39, p. 622. — Lang, 1886, Jena. Zeit. fur Naturwissen., Bd. 19, p. 735. 

 Muhioralis, Mayer, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 54. 



The type species is Gastroblasta timida Keller, from the Red Sea. A second species was 

 found by Lang at Naples, Italy, and another is found at Tortugas, Florida. 



GENERIC CHARACTERS. 



Eucopidae with 2 or more radial-canals and more than 1 manubrium. The tentacles have 

 hollow basal bulbs and the lithocysts are simple, closed sacs each containing a single concre- 

 tion. These lithocysts are numerous and are upon the bell-margin alternating with the 

 tentacles. The gonads are upon the radial-canals. The manubria have typically 4 lips. 

 No peduncle. New radial-canals arise as centripetal in-growths from the ring-canal. 



Gastroblasta timida Keller. 



Gastroblasta timida, Keller, 1883, Zeit. fur wissen. Zool., Bd. 38, p. 622, taf. 35, 5 fign.; Ibid., Sitzungs.Ges.Naturw. Jena., p. 8. 



In large specimens of the medusa the bell is 3 to 4 mm. wide and I to 1.5 mm. high. 

 There are I to 4 manubria and 4 to 17 radial-canals with 17 blindly ending centripetal vessels. 

 The most complex example (fig. 151) was 4 mm. wide, the margin being circular in outline, not 

 elliptical as in G. raffeelet of Naples, where there were 4 manubria near the center of the sub- 

 umbrella. The largest (oldest) mouth was at the center of the subumbrella and had 5 lips, and 

 the 3 other manubria were smaller, and 2 of them had each 3 lips, while the smallest manu- 

 brium was rudimentary and its mouth was undeveloped. The stomachs were all connected one 

 with another by vessels and 17 canals radiated out from them to the ring-canal at the bell- 

 margin. These canals fused irregularly one with another in some instances, but in other cases 

 they extended in a straight line from the stomach to the circular-canal. There was a well- 

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