MAYER : MEDUSiE FROM THE TORTUGAS, FLORIDA. 45 



(centrifugal) side of the tentacles. The proboscis is pyriform, and the lips 

 project beyond the velar opening. The walls of the proboscis are very thin, 

 and the lips are crenulated. The 4 radial canals are broad, and the 4 gonads 

 occupy their proximal halves. In the female each gonad contains about six- 

 large ova, which stand out prominently over the surface of the organ. The 

 entoderm of the proboscis and tentacles is of a delicate shade of green. The 

 genital organs and circular canal are tinged with pink. 



Young Medusa. — Figure 4, Plate 2, represents a young medusa of this 

 species in which the genital organs have not yet made their appearance. 

 There are but 4 tentacles, and 8 ocelli ; and it is remarkable that the long 

 tentacles are as yet solid, although they become hollow throughout their length 

 in the adult medusa. This species is common throughout the summer at the 

 Tortugas, Florida. 



NBTOCERTOIDBS, nov. gen. 

 Netocertoides brachiatum, nov. sp. 



Figs. 43, 44, Plate 18. 



Generic Characters. — Cannotidse with' 8 bifurcating, radial canals. 16 canals 

 reach the circular vessel. There are neither marginal sense-organs nor cirri. 



Specific Characters. — The bell is mitre-shaped and 3 mm. in height. There 

 are 32 marginal tentacles. 16 of these are well developed, and are situated at 

 the bases of the 16 radial canals ; and the others are smaller, and alternate with 

 the large tentacles in position. The large tentacles are only about one quarter 

 as long as the bell height, and the others are much smaller. There are no 

 marginal sense-organs. The velum is well developed. The proboscis has the 

 shape of an 8-rayed star, each ray of which bifurcates, thus giving rise to 

 16 radial canals which reach the circular vessel. The gastric portion of the 

 proboscis is wide, but flat, and the mouth extends but a short distance down into 

 the bell cavity. The gonads appear to be situated upon the 8 rays of the 

 stomach. Two specimens were found at the Tortugas, Florida, on July 10, 

 1898. 



As it floats in the water this medusa bears a wonderfully close resemblance 

 to the little pelagic Alga (Trichodesmium), which is very abundant at the 

 Tortufras. 



