EsTERLY. — Eucalanus. 



PLATE 4. 



All the figures on this plate are cross sections from vom Rath's material and 

 are magnified 1330 diameters; they are to show the nmnber (28) of fibres 

 in the optic nerve. Both frontal nerves (with sharp dark outlines) are 

 also to be seen in each section. Compare Figure 27 (Plate 3). 



Fig. 38. Compare with Figure 1 (Plate 1). The frontal nerves are still sepa- 

 rated from the bundle of optic nerve fibres. 



Fig. 39. A section a few sections posterior to that of Figure 38. 



Fig. 40. Represents a section about midway between the eye and brain. 



Fig. 41. Only a few sections separate this one from the anterior end of the 

 brain. 



Figs. 42, 43. Cross sections through the anterior part of the brain, from 

 another series than that of Figures 38-41. 

 Figure 42. From a section just within the brain. 

 Figure 43. Somewhat posterior to Figure 42. 



