3 mm. 



10mm. 



10 



20mm 



100 



e 



Fig. 14. — Change of proportions in the crab, Carcinus maenas. 



A— D, outline of carapace and of thoracic ganglion in four specimens of different absolute size, 

 to show negative heterogony of interocular breadth {k = 0-85), and of thoracic ganglion (k= 06). 

 The carapace lengths have been made the same for all: actually they were 3-1, 109, 30-0 and 

 71-0 mm. respectively. 



E — H, ommatidia of the same four specimens, all drawn to the same absolute scale. 

 k for ommatidial diameter = 0-32. 



24 



