216 HOMOLOGIES. 
zones of the Sea-Urchin. It is composed of com- 
paratively small perforated plates, through which 
pass the suckers or locomotive appendages ; and 
on either side of the furrows are other plates, 
corresponding to the plates of the broad zones in 
the Sea-Urchin. Where shall we now look for 
the five eyes? Of course, at the tip of every ray ; 
exactly where they were when the rays were 
drawn up to form the summit of a sphere, for 
then the eyes, which are now at the extremities 
of the rays, were clustered together near the point 
of meeting of the five zones on the ab-oral side 
of the Sea-Urchin. Where shall we look for the 
ovarian plates? Ateach angle of the five rays, 
because, when the broad zones of which they 
formed the summit were divided, they followed 
the split, and now occupy the place which, 
though seemingly so different on the surface of 
the Star-Fish, is nevertheless, relatively to the 
rest of the body, the same as they occupied in 
the Sea-Urchin. Assuming, as we premised, that 
the central area of the ab-oral region, forming 
the space between the plates at the summit of the 
zones ifi the Sea-Urchin, is elastic, it has stretched 
with the spreading out of the zones, following the 
indentation between the rays, and now forms the 
whole upper surface of the body. All the inter- 
nal organs of the animal lie between the oral and 
the ab-oral regions, just as they did in the Sea- 
