356 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser- 



one-half the circumference of the parent, one should expect 

 to find that about one-half of the number of buds include 

 the parental siphonoglyph. 



In one case the siphonoglyph of the parent entered the 

 bud accompanied by but one directive mesentery; a second 

 directive with as yet no muscle band apparent was com- 

 pleting the pair in the bud. 



V. Colonies of Three and Four Individuals. 



Four instances of the former and one of the latter have 

 been found. Of the former, three have arisen, each by two 

 divisions in planes perpendicular to each other, the second 

 division affecting but one of the two individuals formed by 

 the first; the method of formation of the fourth is doubtful. 

 The colony of four individuals has been formed as follows: 

 A (fig. I2«) is the original polyp, shown diagrammatical^. 

 B has arisen as a bud upon A, directly opposite to the one 

 siphonoglyph. C and D arose as one bud upon A , at a 

 lower level, this bud dividing later into the definitive individ- 

 uals which have a common oral disk. Figure 12^ repre- 

 sents a section of the column at the level xy. Figure xic 

 represents a section through the oesophageal region of C 

 and D, to show the arrangement of their mesenteries. Mes- 

 enteries 1,2,3, 4> 6, 7, 8 (fig. 12b) appear in C-D (fig. 12c). 

 Pair 3-4 has divided, orally to C—D, one mesentery going 

 to each oesophagus; while aborally to C—D, both mesen- 

 teries (3'— 4') are joined to C. This irregularity is corre- 

 lated with the twist the bud C—D has suffered in the course 

 of its division, for the inner ends of the oesophagi of C—D 

 are in a line at right angles to that connecting their mouths. 

 A further irregularity consists in the behavior of mesentery 

 8, which in D is incomplete orally, complete aborally. Also 

 mesentery 5 does not enter the bud, although its mate, 6, 

 incomplete in the parent, forms a single complete mesen- 

 tery in D. And again, the incomplete mesentery 7, un- 

 paired in the parent, forms two complete mesenteries in D. 

 No directives nor siphonoglyphs could be seen in B, C, 

 andZ>. 



