PLATE IV. 



The lettering is the same in all the fisrures. 



cu Cuticula. 



ec EctoJerm. 

 en Entoderm. 



g Generative organs. 



A Mesenteries. 

 im Intermediary layer. 

 m Muscle-fibres. 



me Mesogloea. 

 ms^ Upper circular muscle. 

 ms^ Lower circular muscle. 



o Ova. 



r Marginal spherules. 

 sr Siplionoglyphe (oesopliageal grooTe) 



t Tentacles. 



All statements giveu as to magnifying j)Qwers have reference to Zeiss's system. 



Aulorcliis paradoxa (sections througli tlie genital tube, figs. 1-6). 



Fig. 1. Connection of an ovum with tlie endoclermal epithelium, probably by means 

 of a thread apparatus (" Faden-Apparat"). E, Oc. 2. 



Fig. 2. Surface view of the germinal layer. I, Oc. 2. 



Fig. 3. Longitudinal section through the germinal layer. E, Oc. 2. 



Fig. 4. Transverse section through the lower part of the genital tube. A, Oc. 2. 



Fig. 5. Transverse section through the upper part of the genital tube, in the region 

 of the oral disc ; the central detritus, which is probably produced by degradation of 

 epithelium, is omitted in the drawing. A, Oc. 2. 



Fig. 6. Epithelial layer from the interior of the genital tube (c£ fig. 4). E, Oc. 1. 



Fig. 7. Ejnzoanthus thalamophilus ; section through the circular muscle (after 

 Erdmann). 



Fig. 8. Horizontal section through the external and the invaginated portions of the 

 body- wall of Ejpizoanthus thalamophilus (after Erdmann). 



Fig. 9. Hormathia delicatula. Portion of the partly invaginated body- wall cut out 

 and magnified slightly. The invaginated part bears the parietal spherules. 



