AGASSIZ AND WOOD WORTH : VARIATIONS IN EUCOPE. 143 



specimen being otiierwise fully developed. In no case was it observed 

 that deficiency or absence of ovaiies entailed a corresponding deficiency 

 or absence of other organs. Reduction or suppression does not occur 

 in any other organ than ovaries in A. aurita. 



H. C. Sorby found, among A. aurita collected in Suffolk and Essex, a 

 " few per thousand " abnormal specimens exhibiting sixfold, fivefold, 

 threefold, and partial twofold symmetry. References to variations in 

 Aurelia, Clavatella, Sarsia, and Stomobrachium may be found also 

 in Bateson's "Materials for the Study of Variation," pp. 421-429. 

 Edwai'd T. Browne examined 383 specimens of A. aurita. He found 

 that eight specimens (2.08%) exhibited numerical variations in the geni- 

 tal sacs, buccal arms, and tentaculocysts. The number of the genital sacs 

 and of the buccal arms varied from three to six. He concludes that 

 there appeared to be a correlation between genital sacs and buccal arms, 

 but that the tentaculocysts vary independently of these. Eighty-seven 

 cases (22.8%) showed variation in the number of tentaculocysts. 

 Twenty of these had less, and the remainder more, than the normal 

 number. The range of variation in tentaculocysts was 6 to 15. 



The preceding observations on the variations of Aurelia show some 

 striking differences from those we have made on Eucope. While in 

 Aurelia there is a general correlation between the number of segments 

 of genital sacs, of buccal lobes, and of tentaculocysts, there is no such 

 correlation in the variations of Eucope. The sense organs in Eucope 

 vary, both in number and in position, irrespectively of the number of 

 radial canals and of segments. Neither multiplication nor abortion of 

 parts ih. Eucope is symmetrical. The suppression of genital sacs is quite 

 common in Eucope, while it is rare in Aurelia. In Eucope suppression 

 is not limited to genital sacs ; as in Aurelia, it extends to the otolith- 

 bearing tentacles. As far as we have observed, the number of terminal 

 folds of the manubrium does not vary in Eucope, and is not correlated 

 to the number of segments. 



The apparatus used in making the photographs was the large photo- 

 micrographic appai'atus of Zeiss, with some modifications, direct sun- 

 light being employed by means of a heliostat of the automatic kind, 

 and all exposures were instantaneous. The camera was always used in 

 the horizontal position, so that with an objective of low power the full 

 length of the bellows could be employed to obtain sufl&cient magnifica- 

 tion with the least loss of light. The objectives employed in photo- 

 graphing Eucope were those of 35 and 70 mm. focus, the lower power 

 being employed with the larger specimens. The exposures were made 



