464 Report of the State Geologist. 



fleshy fold, but soon develops on its inner side a series of small 

 tubercles, which become the tentacles, /. At this stage the 

 lophophore is bilateral, being prolonged to that side where the 

 rectum is to make its appearance. The space between the rudi- 

 mentary tentacles is prolonged downward, being the first trace 



Fig 27. PaludicellaEhrenhergi. Free spermatozoa (after Allman). 



of the body of the polyp, g. The embryo is now suspended in 

 a membranous sac from the walls of the cell. A few minute 

 fibers can be observed, which develop into the polyp retractors. 

 In A, the tentacles are much more developed ; the body of the 

 polyp is prolonged downward, and we are able to trace the 



Fig. 28. Pahulicella Ehrenbergi, showing manner of growth (after Allman) . 



positions occupied by the oesophagus, stomach and intestine. The 

 tube retractors can now be observed as a few indistinct fibers. 



