THE HYDROMEDUSAE 



25 



cnidoblasts. On the outer edge of the bell are also found in some 



Fio. 32. 



Fio. 30. 



Fio. 34. 



Fi(i. 33. 



30.— Small portion of a hydrocladiuin of a Pluinularian hydroid. Between two annnlationi; 

 of the hydroclaiiiuMi lie (") a liydroid projecting froin its hydrotheca ; ('<) above it two 

 lateral neniatoiihores (inoditie<l hydroids), one of which is expanded ; (c) below it a single 

 median neinatophore, also expanded, and spreading over the hydrotheca. (After Allnian.) 



31. — Perisarc of a small portion of a hydrocladium oX Aglwyj'lunxa filicu!a, viewed at right 

 angles to the plane of Fig. 30, showing between each two annulations of the hydrocladinm, one 

 hydrotheca, two lateral and one median seniituhular thecae for neniatophores. (After Alhnan.) 



32.— Diagram of the flattened medusoid of Obelia, showing two of the four perradial canals 

 with the iiendent gonads, four of the eight adradial otoeysts. 



33.— View of the oral surface of one of the Leptomedusae (Ircnt jvlhtcida, Haeckel), to 

 .show the numerous tentacles and the otoeysts. ge, genital glands ; M, manubrium ; ot, otoeysts ; 

 re, the four radiating canals ; Vc, the velum. (From Lankester.) 



34.— Part of the edge of the bell of a Leptomedusan. CC, circular canal; ^[C, marginal 

 cirrhus ; MF, marginal funnel ; .1/7', marginal tuliercle ; ItC, opening of radial into circular 

 canal; 7', tent<icle (cut short) ; F, velum. (Modified from Haeckel.) 



genera marginal tubercles, slight prominences on the body wall, 

 generally containing a prolongation of the coelenteron, often 



16 



