*COMMENT ~ Ephemeroptera: Character notes. 
 
*CHARACTER NOTES 
#2-16:18-23. Sub-imagines other than those of \i{}Caenidae\i0{} are
distinguishable from imagines by their fringed, relatively dull wings,
and those of males have incompletely developed genitalia. Both
imagines and sub-imagines of the \i{}Caenidae\i0{} are supposed to key
out together via the characters offered. 
#17. This character is emphasized in the otherwise rather different
keys presented by Kimmins (1954) and Imms (1957), probably because it
featured in Ulmers (1933) classification, but the details need
checking. While Kimmins states that in the Baetidae, the hind tarsus
has the appearance of only 3 free segments, the two basal ones being
fused to the tibia, his drawing of the hind tarsus of \i{}Cloeon
dipteron\i0{} shows four (as also do Harkers diagrams of both
\i{}Cloeon\i0{} and \i{}Procloeon\i0{}). \par{} Sub-imagines other
than those of \i{}Caenidae\i0{} are distinguishable from imagines by
their fringed, relatively dull wings, and those of males have
incompletely developed genitalia. Both imagines and sub-imagines of
the \i{}Caenidae\i0{} are supposed to key out together via the
characters offered. 
 
