232 ^ DONALD WALTON DAVIS 



ToRREY, Harry Beal, and Mery, Janet Ruth 1904 Regeneration and non- 

 sexual reproduction in Sagartia davisi. Univ. Cal. Pub., Zool. 1, 

 pp. 211-226. 



Verrill, a. E. 1869 Our sea-anemones. Amer. Nat., 2, pp. 251-262. 



Yule, G. Udny 1900 On the association of attributes in statistics. Phil. 

 Trans. Roy. Soc., London, (A) 194, pp. 257-319. 



SYMBOLS USED IN TABLES AND FIGURES 



The following symbols appear as subordinate headings under Old and New- 

 Mesenteries in tables 3 to 8: 



B, bounding mesentery, i.e., a mesentery adjacent to the boundary of the new 

 or old region in which it lies and without a mate in that region. The mesentery 

 occupying this region is represented whether incomplete or complete. 



D, directive mesenteries, which occur in pairs. 



N-D, complete mesenteries which are not bounding mesenteries nor directives. 

 With rarest exceptions they are found in pairs. 



The symbols below are used in table and figures to designate specific mesen- 

 teries. 



In bold face they represent mesenteries formed during ontogenetic develop- 

 ment or in the oldest regenerating region distinguishable in that specimen. 



In italic type they indicate mesenteries regenerated after the recorded division. 



In roman type they represent mesenteries of intermediate age. Sone of 

 these may have been incompletely developed at the time of the latest division. 



d, a directive mesentery. 



c, a non-directive mesentery, actually complete or destined to become so. 



c\ c^, c^ c'', regenerated non-directive mesenteries, actually or potentially 

 complete, whose positions with respect to the new directive plane are indicated 

 in the figures by exponent numerals. 



c?, a mesentery now complete, but possibly derived from an incomplete one 

 through abnormal fusion with the esophagus. It is consequently doubtful 

 whether this was complete when fission took place. 



(I), a member of the most advanced cycle of incomplete mesenteries repre- 

 sented in an individual. 



(II), (III), members of the second and third cycles of incomplete mesenteries 

 found in the specimen. 



(1), a permanently incomplete mesentery of undetermined grade. 



(1)?, an apparently incomplete mesentery which was probably derived from a 

 complete one by being torn from the esophagus. 



* symbol indicating absence of any unpaired mesentery adjacent to the 

 boundary between old and new parts, i.e., the boundary lies in an exocoel. 



t symbol used in table 5, no. 18b and no. 22b (and in table 10 referring to the 

 same specimens) to designate the bounding conditions when a second fission plane 

 has passed through the boundary between old tissue and tissue regenerating 

 following a shortly preceding division. 



Four, five, etc. (tables 3, 5, 6), number of small mesenteries in a regenerating 

 region at a stage of development too early to indicate the final formula. 



