408 



Prof. J. 1*^. Duerden on the 



tlirougli an entire polyp, and reveals tliree thickened down- 

 growths extending into tlie ]iolypal cavity for about two 

 thirds the length of the polyp, a distance much beyond the 

 mesenteries which separate one downgrowth from the other. 

 They vary somewhat in length, as indicated in the figure. 

 The downsrrowth to the ri"-ht is shown attached to the disk 



Fijr. 1. 



Vertical section tlirougli a decalcified polyp, passing through three 

 intrapolypal tentacles and four mesenteries. The latter extend 

 down-n-ards for only a short distance, the uioditied tentacles far 

 exceeding them in length. The section passes to one side of the 

 stomodaeum. 



above, and the mesogloea of the latter is continued down the 

 centre as a kind of supporting axis; the other two are here 

 shown free from the disk, though in other sections the con- 

 tinuity is shown. Fig. 2 represents a section through the 

 stomoda?ura of another polyp; here the single downgrowth 

 to the lett clearly corresponds in position with the normal 

 tentacular upgrowth to the right and is much longer. 



