esterly: eucalanus. 19 



coincides with the chief axis of the eye. The cells which cadjoin the 

 central one, above and below, are, respectively the central cell of the 

 upper and lower groups; the long axes of these cells are nearly at right 

 angles to each other. The long axis of the dorsal cell is parallel to 

 the dorso-ventral axis of the median eye, while the axis of the ventral 

 cell is perpendicular to the median plane of the body. Similar rela- 

 tions are shown in the cross sections of the eye represented in Figure 9 

 (Plate 1) and Figure 23 (Plate 2). 



An examination of frontal sections (Plate 1, Figs. 2, 5) through^jhe 

 lateral eyes, or of entire preparations (Plate 1, Fig. 10, Plate 2, Fig.^2) 

 gives an idea of the position of the axes of some of the other cells of 

 the lateral eyes. It will be seen in Figures 2 and 5 (Plate 1) that the 

 axes of the peripheral cells of a group if prolonged would meet at an 

 angle of about 90° at their outer ends. In Figure 2 the three nuclei 

 shown in each of the lateral eyes belong to the cells of the median group 

 of three. The central cell is seen to be triangular in outline, and the 

 anterior and posterior cells are elongated. In Figure 22 (Plate 2) the 

 outlines of the cells in the right lateral eye are shown, but merely in 

 the most general w^ay, for it is impossible to indicate the cell walls in 

 perspective, and even if it were attempted, the result would be con- 

 fusing. But the figure shows well enough the relations that the axes, 

 of the anterior and posterior cells of the groups bear to each other, 

 and it also indicates the general shape of the various cells, the cen- 

 tral ones of each group being triangular, the others more elongated 

 and extending from the base of the cup to its outer margin. 



With the relations of the axes of the cells of the lateral eyes in mind, 

 inspection of such a cross section as is shown in Figure 7 (Plate 1) 

 will convince one that the interior bodies have an arrangement that 

 corresponds, at least in a general way, with the long axis of the cell. 

 It will be seen that in the three cells forming in this section the median 

 border of the lateral eyes these bodies are so arranged that they lie 

 lengthwise of the cells. Not all the interior bodies have been repre- 

 sented in this drawing, but special care has been taken not to select 

 those only which would prove the point here contended for. The 

 illustration gives an accurate general idea of the arrangement of the 

 rod-like or spindle-like bodies in the central cells. Even in such a 

 seemingly heterogeneous assemblage of interior bodies as is shown in 

 the lateral eyes in Figure 9 (Plate 1), a definite arrangement with 

 reference to the cells is apparent; and the. same may be said of Figure 

 23 (Plate 2). 



In frontal sections a similar arrangement of the interior bodies with. 



