220 THE MEDUSAE. 



Proboscidactyla ornata McCrady var. stolonifera Maas. 



Willaia ornata McCrady, '57, p. 149, pi. 9, figs. 9-11. 



Willia ornata A. Agassiz, '65, p. 177, figs. 174 a-%79 ; Fewkes, '82 b , p. 299, figs. 22-24. 



Willetta ornata Haeckel, '79, p. 157. 



Discannota dysdipleura Haeckel, '79, p. 152. 



Proboscydactyla ornata Browne, : 04, p. 726. 



Proboscydactyla flavicirrata var. stolonifera Maas, : 05, p. 21, taf. 4, figs. 24-28. 



Proboscydactyla tropica Browne, : 04, p. 727. 



Willia occideutalis Fewkes, '89 b , p. 109, pi. 5, fig. S. 



Proboscydactyla varians Browne : 04, p. 728, pi. 54, figs. 1, 2. 



Plate 6, Figs, l, 2; Plate 41, Figs. 1-7. 



Acapulco Harbor ; surface ; many specimens, 2.5-5 mm. in diameter. 



There has likewise been available for comparison a series of excellently 

 preserved specimens of P. ornata from Newport, R. I. Specimens from 2.5-3 

 mm. in diameter are indistinguishable from the Newport series, the extent 

 of the gonads, and the number of canals and tentacles (12-16), as well as the 

 mode of branching of the canals being the same in both forms. So far as 

 I can learn sixteen is the normal limit to the number of canals and tentacles 

 in the Atlantic P. ornata ; many of the Acapulco specimens, however, have 

 seventeen, eighteen, or even nineteen tentacles, and the same is true, 

 according to Maas (: 05) of the "Siboga" specimens. And since these num- 

 bers were counted in the largest specimens (4.5 mm. in diameter) it is fair to 

 assume that this increase is normal for the Pacific race. Such an increase 

 would not be at all surprising as a variation in P. ornata, since exactly this 

 same type of variation has been described by Browne ('97) for the European 

 Willia stellala; but I have been unable to find any evidence that it actually 

 occurs in P. ornata from the Atlantic. 



The only other difference (except in size) between the present series 

 and P. ornata is afforded by the gonads. In Atlantic specimens the limit of 

 development of these organs appears to be a stage in which they have 

 extended from the gastric wall outward along the line of the radial canals 

 nearly to the first bifurcation of the latter. This stage, however, seen in P. 

 ornata var. stolonifera of about 3 mm., is not the final one in that form, for 

 with the further growth of the Medusa the sexual organs extend further, 

 until they nut only reach the division of the canals, but even pass beyond 

 it, ho that, anally a portion of the gonad comes to lie in each of the four angles 

 formed by the branching of the canals (PI. 41, fig. 4). 



