216 Dr. A. KorotnefF o?r Poljpaviura ambulans. 



Scyphistoma^ which, for various reasons, we must regard as a 

 most simple and primitive Actinia, the above-mentioned 

 longitudinal muscles are placed, as has been described in the 

 case of the directional septa, in close relation to the buccal 

 aperture. Hence the arrangement of the muscles on the direc- 

 tional septa, in which the archetypal form is to be seen, is 

 indicative of various homologies. In this way, then, the 

 relation of the muscles to the septa in Polyparium is not 

 abnormal, but, on the contrary, quite typical. 



I may further mention that if the principle established by 

 HoUard is applicable in general and not in details to the 

 Actiniai, it nevertheless loses its significance outside this 

 group. Thus in a transverse section of an Alcyonium we 

 see, as the brothers Hertwig have shown (see fig. II.), that in 

 the circumference of the section there is a point, looking from 



Fig. II. 



Transverse section through a polyp of- Alcyonium: rs, directional 

 septa; /, muscular bauds. (From the work of the brothers 

 Hertwig.) 



which all the septa have the muscles turned away, four on 

 the right and four on the left-hand side, and a second opposite 

 point, looking from which the muscles are turned towards it; 

 in other words, we find the longitudinal muscles turned to- 

 wards one another, in accordance with Hollar d's principle, 

 only on one pair of the directional septa, all the others being 



