JOO 



GENERAL PRINCIPLES OF ZOOLOGY. 



FIG. 82. Haliomma erinaceus. n, external, /, internal, latticed spherical skeleton; ck, cen- 

 tral capsule; w, extra capsular soft parts; , nucleus. 



zr 



* 



FIG. 83. Nausithoe, an acrasped medusa (after Lang}, seen from the end of the greatly- 

 shortened main axis. pr, perradii ; fr, interradii ; ar, adradii (perradii and interradii 

 mark the four planes of symmetry of the animal); sr, subradii ; rl, mantle-lobes ; f, ten- 

 tacles ; s&, sensory organs ; g, sexual organs ; gf, gastric filaments ; /, subumbrellar cir- 

 cular muscle ; in the centre the cross-shaped mouth-opening. 



