PLATE III. 



The lettering is the same in all the figures. 



cu Cuticula. 

 cc Ectoderm. 

 en Eulioderm. 



(J Generative organs. 



A Mesenteries. 

 1711 Intermediary layer. 



me Mesogloea. 

 M!,^ Upper circular muscle. 

 «i.f' Lower circular muscle. 

 Ova. 



r Marginal spherules. 

 sr Siphonoglyphe (cesophageal groove). 



m Muscle-fibres. ' t Tentacles. 



All statements given ns to magnifying powers have reference to Zeiss's system. 



Fig. 1. Circular muscle of Stephanidium schulzii ; — la, in the region of an inter- 

 mesenterial chamber and of a marginal spherule; lb, in the region of the origin of a 

 mesentery. 



Aulorchis paradoxa (figs. 2-6). 



Fig. 2. Transverse section through the oral disc. A, Oc. 1, somewhat diminished. 



Fig. 3. Parts of a transverse section through the circular muscle, showing the 

 connection of the endodermal and mesogloeal muscle-layers : 3a, with D, Oc. 1 ; 36, 

 with E, Oc. 1. 



Figs. 4, 5. Sections through the stomidia. a^, Oc. 1. 



Fig. 6. Transverse section through the mesogloeal musculature of the oral disc. 

 D, Oc. 1. 



Fig. 7. Stephanidium schulzii ; upper edge of the body-wall, x 60. 



