424 



MERISTIC VARIATION. 



[part I. 



I. Cgelenterata. 



f 630. Sarsia mirabilis 1 : normally four radial canals, &c. (Fig. 127. 

 I and III). Out of many hundreds of N. American specimens 

 two were found with six radial canals, six ocelli, and six tentacles, 



Fig. 127. Sarsia mirabilis. I and III, the normal form, with four radii, from 

 below and from above. II and IV, an abnormal form with six radii, from below 

 and from above respectively. (From Agassiz.) 



symmetrically arranged (Fig. 127, II and IV). These specimens 

 were of larger absolute size than the normals. Agassiz, L., Mem. 

 Amer. Ac. Sci., iv. p. 248, PI. v. fig. 5. 



1 Sarsia is the medusa of the Gymnoblastic Hydroid Syncoryne. 



