186 THE MEDUSAE. 



genus, where the medusae are little more than detached gonophores, such 

 clues, especially when taken from only one specimen, cannot be relied upon 

 without a knowledge of the hydroid, it is best to leave it for the present 

 without specific identification. 



Pennaria vitrea Agassiz and Mayer. 



Pennaria vitrea Agassiz and Mayer, '99, p. 161, pi. 1, figs. 1-2. 



Plate 7, Fig. 4. 



Station 4696; surface; 1 specimen, 4 mm. high by 3 mm. in diameter. 



These dimensions are slightly larger than those given by Agassiz and 

 Mayer, to whose account I have little to add. The specimen had discharged 

 its sexual products, and the manubrium was somewhat shrivelled. The 

 four tentacular bulbs are extremely rudimentary ; exumbrella surface 

 smooth; radial canals unpigmented. 



Color. — The tentacle bulbs are yellowish; the manubrium opaque and 

 milky. Agassiz and Mayer ('99) state that the entoderm of the manubrium 

 in both sexes is green ; but Hargitt has shown that color is a variable 

 character in this genus. 



Pennaria species? 

 Plate 7, Fig. 6; Plate 40, Fig. 7. 



Acapulco Harbor ; surface ; one specimen, 2 mm. high. 



This specimen, which had discharged its sexual contents so that the 

 manubrium is much shrivelled, closely resembles the medusae of P. tia 

 relict, which I have examined in large numbers, except for its more bril- 

 liant coloration, and for the fact that the radial canals have swellings 

 about midway of their lengths. These swellings appear to have nothing 

 to do with the formation of sexual products, but are merely crowded with 

 pigment granules. 



The bell is high and narrow; the gelatinous substance stiff and opaque; 

 tli.' tcut.i.lc |)nll,s very rudimentary; the manubrium about half as long as 

 the bell height. 



r. — The color of this Medusa is very brilliant, the manubrium and 

 radial canals being brick-red. Tentacle bulbs colorless. 



This specimen differs from any Medusa previously referred to Pennaria; 



