410 ARTHUR T. MA«TERMAN. 



cliiata, the tentacles of numerous sedentary Annelida and 

 Brachiopoda, Cepha Iodise us, and even tlie branchial 

 filaments of Tunicata and Amphioxus. These resem- 

 blances depend upon a similar method of food ingestion, the 

 cilio-trophic, in each of the groups, and it seems fairly clear 

 that in each case the branchial function has been only secon- 

 darily added. In Phoronis not only does this filtration 

 method hold, but the trophophoral epithelium has glandular 

 cells distributed in it. As the result of the activity of these 

 cells fine strands of mucus pass down the oral side of the 

 tentacles and serve to entangle minute algoid bodies. In 

 fig. 8 these strands with their contents may be seen passing 

 along the oral side of the epistome into the oesophagus. 



Lastly, the epistome itself is so arranged in relation to the 

 rest of the lophophore that it acts as an organ to remove the 

 water from the oral aperture. 



Figs. 60, 61, and 62 are intended to illustrate this point. 

 The coils of each half of the lophophore are arranged spirally, 

 and the tentacles are widely separated from each other for 

 about their distal two thirds and united together laterally 

 for the proximal one third. A transverse section of the 

 lophophore may illustrate the arrangement at different 

 heights. 



Thus in fig. 59 the outermost half-coil shows the tentacles 

 cut in transverse section, each having the trophophoral 

 epithelium on its oral surface and filtration spaces between 

 contiguous tentacles. For the rest of the course of the coil 

 the deeper parts are cut in which the tentacles are fused to- 

 gether laterally, so that the tentacular filtration method no 

 longer acts at this depth. But not very far up, at the 

 beginning of the second coil in the figure, the epistome may 

 be seen in transverse section projecting across the fl.oor 

 of the oral aperture for a little over a coil in length. 

 After this the section is too deep to cut the epistome 

 completely with its ectodermal epithelium, but its coelomic 

 cavity can be seen in transverse section up to the very tip 

 of the spiral. Benham (1) criticises Allman^s description 



