PLATE I. 



Fig. I. Transverse section of sphincter of a specimen of Me- 

 tridium dianthus measuring 1.5 cm. in height (Leitz 

 I, 3, camera). 



2 . Transverse section of sphincter of a specimen of Metri- 



diiim dianthits measuring 8 cm. in height (Leitz I, 

 3, camera). 



3. Transverse section of sphincter of a specimen oi Metri- 



diiim dianthus measuring 3 cm. in height (Leitz I, 

 3, camera). 



4. Transverse section of a mesentery of the first cycle of 



Metridhmi dianthus (Zeiss a, Leitz I, camera). 



5. Transverse section of a directive mesentery of Metri- 



diuni diantJius (Leitz I, 3, camera). 



6. Transverse section of sphincter of Urticina crassicornis 



Leitz I, Zeiss a, camera). 



7. Cribrina elegantissima, from a preserved specimen. 



Natural size. 



(48) 



