I50 



H. B. TORREY. 



Table IX. 



Colony with 28 Hydrocladia. 

 Measurements, in mm. X 95 > of the profile width of each hydrotheca in Fig. ''3 to 

 the point of ( i ) the mesial nematophore on a line perpendicular to the axis of the 

 internode (lower figures), and (2) the length of the mesial nematophore on the same 

 line (upper figures). 



Table X. 



Same colony, showing angles made with the axes of their internodes by the planes 

 of the hydrothecal openings, the latter being represented in each case by a line tangent 

 to the depressions between lateral marginal teeth i and 2, and 4 and 5 (see Hd. 10, 

 hth. 8). 



is smaller than the others, and there is a distinct tendency toward 

 a reduction of the obliqueness of the hydrothecal opening, from 

 base to tip. The mesial nematophore, also, projects farther from 

 the hydrotheca in the intermediate internodes than at either 

 extreme of the hydrocladia. 



A. struthionides. — The obliqueness of the hydrothecal open- 

 ings in each hydrocladium is practically constant in this species 

 (Fig. 4). As in A. octocarpa, however, each hydrocladium tapers 

 from base to tip, and the mesial nematophore is most prominent 

 between the extremes. The prominence of the nematophore is, 

 perhaps, of all the characters, most useful to the experimenter. 

 The measurements in Table XL show that the length of the 

 nematophore along a line passing through its tip and perpendicu- 

 lar to the axis of the internode, varies independently of the width 



