196 C. M. CHILD. 



oblique surface (Fig. 4). No traces of tentacles wete visible else- 

 where. In the third piece the unpigmented tentacular ridge was 

 visible at the most oral portion of the oblique surface but tentacle- 

 buds had not yet appeared. 



Controls. A. Closed and distended : marginal tentacle-buds 

 just appearing on the whole circumference ; slightly less advanced 

 than the most oral portion of the two experimental pieces with 

 tentacles. B. Closed and more or less distended but no tentacle- 

 buds visible. 



September ig. 7 days after section. Experimental pieces : 

 All closed and distended : marginal tentacles on the most oral 

 portion of the oblique surface 23 mm.; from this region decreas- 

 ing in length on each side, the lower three fourths to two thirds 

 of the oblique surface still without tentacles. 



Controls. A. Marginal tentacles 2-3 mm. about whole cir- 

 cumference. B. Marginal tentacles 1 1.5 mm - about whole cir- 

 cumference. 



September 22. 10 days after section. Experimental pieces : 

 Marginal tentacles longest on upper side of oblique disc, decreas- 

 ing to o toward lower side. In none of the three specimens are 

 tentacles present on the lowest portion of the oblique disc : in 

 one specimen the longest tentacles are 5-6 mm. and the circle of 

 tentacles is nearly complete (Fig. 5) ; in the second the longest 

 tentacles are 3-4 mm. and the lower one third of the disc is 

 without tentacles ; in the third the longest tentacles are 2-3 mm. 

 and about one half of the disc is still without tentacles. This 

 piece has been somewhat retarded throughout by irregular in- 

 rolling at the aboral end delaying closure and distension. 



On the three more advanced pieces labial tentacles are appear- 

 ing on the upper one third to one half of the disc (Fig. 5). 



Controls. A. Marginal tentacles 5 6 mm. about whole circum- 

 ference. B. Marginal tentacles 34 about whole circumference. 



September 26. 14 days after section. Experimental pieces : 

 In the most advanced piece (Fig. 6) the longest marginal tenta- 

 cles on the upper side of the disc are 10 mm., the shortest on the 

 lower side 2 mm. Labial tentacles are present on the upper 

 two thirds of the disc, the longest being 3-4 mm. (Fig. 6). 



In the second piece the tentacles are equal in length to those 

 of the first and show a similar arrangement. 



