57© Chas. W. Hargitt. 



be unbranched, and as Browne admits in another connection 

 (p. loi), there is good reason to beHeve that its position may 

 shift considerably. 



Figures 12, 14 and 15, are careful drawings of variant 

 canal features, in each of which there is shown at a an adradial 

 rhopalium, while in one case, Fig. 14, the canal is some- 

 what branched, but taken in its relations with both the other 

 canals I see no other alternative than to regard it as adradial. 

 This is also shown at A^ Plate I, Fig. 2. 



Both Ehrenberg and Ballowitz (op. cit.), have figured similar 

 cases of undoubted adradial rhopalia. 



The chief variations found in rhopalia are those of number 

 and position, the later of which has just been noticed. The 

 smallest number found was five, only a single specimen among the 

 entire lot studied having so few. Six were found having but six 

 rhopalia. Others having larger numbers are tabulated in their 

 appropriate places in the various tables. As will be seen the 

 largest number found was fifteen, and in but a single specimen. 

 This specimen was further peculiar in having two fully developed 

 and functional mouths, as shown in Fig. 10. This duplex oral 

 condition served to give the animal a somewhat ovoid shape and 

 at the same time a more or less bilateral aspect, the latter being 

 further accentuated by the presence on almost exactly opposite 

 sides of two compound marginal lobes and rhopalia, as shown in 

 the figure. 



A similar condition so far as the marginal lobes and rhopalia 

 are concerned is shown in Fig. 9. In this case there are three 

 compound lobes, but they do not tend in any way toward either 

 bilateralism or even a trimerous form. An additional compound 

 lobe w^ould -have rendered the variation a strikingly sym- 

 metrical one. But like the former and several others of a similar 

 character which came under observation there was seldom exact 

 symmetry. 



The effect of less or more than the normal number of rhopalia 

 may, or may not, disturb the general radial symmetry of the 

 umbrella. For example, in Plate I, Fig. i, is shown a medusa 

 w^ith but seven rhopalia, yet the general symmetry seems quite 

 normal. By a careful inspection it is not difficult, however, to 

 discover that one of the interradial systems is entirely lacking. 

 Again in Plate I, Fig. 6, of a hexamerous specimen, there are 



