GONIONEMUS. 105 



Gonads. — These, as in G. corynetes, are simple folds extending along the 

 oral surfaces of the radial canals, without papillae or secondary plications. 

 They occupy about the central third of the canals. In the single specimen 

 they are full of moderate-sized ova. 



Color. — The specimen was not examined until after preservation. 

 Gonads, tentacles, and manubrium are pale yellowish brown, and the bell 

 hyaline. In G. corynetes there are one or two red or brown spots at the base of 

 each tentacle group, but these are lacking in G. hrachymera. 



The presence of a well-marked peduncle serves to separate this species 

 from G. corynetes, and may be considered its most important specific character. 

 The condition of the tentacles is also of taxonomic value, the large size of 

 the single perradial tentacles, and the presence of rudimentary papillae on 

 the bell margin sharply distinguishing it from the North Atlantic species. If, 

 as seems probable from the advanced state of the sexual organs, the number 

 (two) of members in each tentacle group is the final one, this forms another 

 important difference between the two species. 



Gonionemus A. Agassiz, 1862. 



Olindiinae with four radial canals ; without centripetal canals ; with a 

 single series of tentacles not in groups ; each tentacle with a sucking disc. 



Since the description of the original species of this genus, Gonionemus 

 vertens, by A. Agassiz ('65), six additional species have been described : — G. 

 murbacJui Mayer (: 04), G. SMiJaej2S2s Agassiz and Mayer ('99), G. depressum Goto 

 (: 03), G. agassisii Murbach and Shearer (: 03), G.pelagicus Bigelow (: 04), and 

 G. Jiornelli Browne (: Oo*"). Fortunately, all these have been well described and 

 figured. I have been able to examine specimens of G. vertens (type), G. 

 siwaensis (type), G. pelagicus (type), and a very considerable series of G. 

 murbachii, in addition to the specimens in the present collection. 



The species fall into two well-marked groups : — 



A. With sixteen otocysts ; with the gonads distal, occupying from one 



fourth to one third of the radial canals. This includes G. siivaensis, 

 G. hornelli, G. pelagicus. 



B. With at least as many otocysts as tentacles ; number of otocysts 



variable ; gonads occupying nearly the entire length of the radial 

 canals ; G. vertens, G. agassizil, G. depressum, G. miirbachu. 

 I have not been able to find good distinctions between the three " spe- 

 cies " of group A, All have about the same number of tentacles (seventy to 



