128 MARINE INVERTEBRATES 



Island Sound northward. It is from four to twelve inches high. The 

 main stem is in long spiral turns, and at intervals has spreading plumose 

 branches. The zooid-cups are tubular and closely pressed against one 

 another, and are ranged in rows on one side of the branchlets ; the aper- 

 tures of the cups are plain and oblique. (Plate XLIII.) 



FAMILY GEBYONOPsmas 



GENUS Tima 



T. formosa. A very delicate and transparent medusa ; size one to 

 two inches in diameter ; bell conical ; radial tubes four in number ; 

 manubrium long, hanging far below the disk ; four frilled appendages 

 diverging from the corners of the mouth ; tentacles thirty-two ; egg- 

 sacs white and following the line of the radial tubes in undulating folds. 

 This species is not very common ; it is found on the New England coast. 



FAMILY JEQTJOBEIDJE 



GENUS Zygodactyla 



Z. groenlandica. Medusa 

 seven to eleven inches in diam- 

 eter ; disk violet-colored and 

 transparent ; margin fringed with 

 long, fine, contractile tentacles of 

 a darker violet color ; numerous 

 radiating tubes; egg- sacs in 

 slightly waved plates; manubrium 

 hanging below the line of the disk 

 and with a thin frilled membrane 

 depending from it. Found north 

 of Cape Cod in July. 



ORDER TRACHYLINJE 



The Trachymedusce are characterized by their direct develop- 

 ment, the egg of the jellyfish producing a medusa and not a 

 hydroid colony. 



GENUS Trachynema 



T. digitate. Size one inch to one and a half inches in height ; rose- 

 colored ; the bell thin and hard, and conical at the top. The swimming 

 is effected by contractions of the muscular velum (the band around the 

 inner margin of the umbrella) instead of wholly by the bell. The ten- 

 tacles are long and numerous, and are curled up when moving. The 

 manubrium is long and has four expansions at the mouth. Eight egg- 



