270 



J. Playfair Mc Murrich, 



In accordaiice with tlie multiplicity of stomatodaea the arrange- 

 ment of the mesenteries presents considerable iri-egularity as may 

 be Seen from text-fig-ure A, which represents the conditions in the 

 Upper part of the column of one of the smaller specimens from 

 Puerto Montt. From this it will be seen that in this individual 

 there were altogether eig-hty-five pairs of mesenteries, showing- a 

 general grouping- around the large central stomatodaea, combined 

 with a subordinate grouping around the more peripheral smaller 

 ones. At one portion of the circumference there seems to be a 

 tendency for the perfect mesenteries to alternate with imperfect 

 ones, but in another portion all the mesenteries are perfect, and this 



Fio-. A. 



is true with regard to both the primary and the secondary grouping. 

 In another individual with only a Single central stomatodaeum sixty- 

 five pairs of larger mesenteries were counted and in addition thirtj^- 

 three pairs of smaller ones; the larger pairs seemed to show a 

 tendency to be alternately perfect and imperfect, but frequent 

 disturbances of such an arrangement occurred. Each of the smaller 

 stomatodaea had in connection with it a Single pair of directives; 

 the central stomatodaea in the individual represented in text-figure A 

 had in one case one pair and in the other two. 



The longitudinal muscle pennons were fairly well developed 

 (Fig. 58), consisting of comparatively few, but high and branching 

 mesogloeal processes. In the upper part of the column, the process 

 at the outer edge of the muscle was larger than the others and 

 gave rise to numerous lateral processes, so that the pennon seemed 



