THE PALE WATERY SPINNERS 31 



according to the species, and as may be seen in 

 Plate III, in Baetis binoculatusthe eyes are lemon 

 or bright yellow ; in Baetis scambus they are 

 clove or sepia-brown ; in Centroptilum lutecium 

 they are bright light red ; and in Centroptilum 

 pennulatum light cadmium-orange. The genus 

 Baetis may be distinguished from Centroptilum 

 by the number of lines between the main ner- 



FiG. 8. Fore-wing of Baetis species. 



FIG. 9. Fore-wing of Centroptilum species. 



vures of the fore-wings. It will be found that 

 there are two such lines in Baetis, and one only 

 in Centroptilum. In Figs. 8 and 9, the differ- 

 ence in neuration between the fore-wings of 

 European species of Baetis and Centroptilum 

 may be observed. 



