42 McMURRICH 



I may add that Mr. H. B. Torrey has recently informed me 

 that in all the specimens of E. prolifera which he has examined, 

 the sphincter was of the circumscribed sessile type. 



In Fig. 27 is represented a section through a portion of the 

 column wall bearing one of the embryos. It shows that the 

 embryos are in an early stage of development, having just 

 reached the stage at which the stomatoda^um {si) is being in- 

 vaginated. The ectoderm of the embryo {c. ec) forms a con- 

 tinuous sheet completely separated at every point from the 

 ectoderm of the parent {ec) on which it rests, and it is evident that 

 the embryos are not buds, but really egg-embryos which have 

 become attached to the surface of the adult actinian and are 

 held there by the mucus {jn) secreted by the numerous 

 ectodermal gland cells. 



In the specimens which Verrill ('69) originally examined and 

 which he has recently figured ('99) the attached embryos had 

 reached a much more advanced stage of development than those 

 just described, the smallest one having twelve tentacles and the 

 largest twenty-four. Verrill seemed inclined, in his earlier 

 paper, to regard the embryos as buds and states that they 

 "probably derive nutriment from the parent." In his more re- 

 cent account he evidently recedes somewhat from this position 

 and I may point out that it seems clear from what I have stated 

 above as to the distinct separation of the embryos from the 

 parent that they are not nourished by the parent in the sense 

 that there is any communication between the cavities of the 

 parent and those of the embryos. 



The tentacles are thin-walled and their ectodermal muscula- 

 ture is but feebly developed. The radial musculature of the 

 disk is fairly strong in its peripheral portions, but more centrally 

 it is very feeble ; it is throughout ectodermal. 



In the region of the lips the mesoglcea becomes considerably 

 thickened forming ridges corresponding to the ridges of the 

 stomatodaeum. Occasionally, though not always, the tip of 

 one of the thickenings seems to be separated from its main 

 portion by a slight interval, producing a minute tubercle im- 

 mediately external to the lips. The stomatodaeum is ridged and 



