MEDUSA. I. 



85 



Table X. Synopsis of the Results, obtained from Table IX. 



in table X. The columns of this table give the average diameter of specimens with so and so many- 

 tentacles. The differences between tlie figures for the various regions are not larger, but that they 

 may be due to casual variation and different degree of contraction. This is most obviously seen, when 

 the figures are represented by curves, one curve representing the results for each of the areas (textfig. 

 14). The 5 curves cut each other in a quite irregular manner in different points, at the same time as 

 their courses are mainly alike. 



A feature, which may be characterised by means of mere countings, being independent on 

 contraction or other phenomena produced by preservation, is the situation of the marginal vesicles in 

 relation to the tentacles. A numeral expression of this situation may be attained in the following 

 manner. In each individual we count the number of tentacles situated between the two marginal 

 vesicles of one and the same quadrant (i. e. around the interradials of the animal), and the number of 

 tentacles between the two marginal vesicles situated on either side of one and the same radial canal 

 (i. e. around the perradials of the animal). When one of the figures found is divided by the other, we 

 obtain a numeral expression of the place of the marginal vesicles in the specimen in question. For 

 the sake of brevity I use the letter / to represent the number of tentacles in the interradial spaces 

 between the marginal vesicles, whereas the letter p represents the number of tentacles in the perra- 

 dial spaces. Then I operate with the quantity -. . This quantity appears to be highly variable. One 

 should expect it to keep tolerabl\- near i, but as will be seen from the table, the value may vary 



between about 0.8 and 1.5 within one and the same localitv. It will be seen from table IX that there 



P 

 is no correlation between — and the absolute total number of tentacles. Table X gives the average 



value of - . within each of the geographical regions, the standard deviation, and the lowest and highest 



