168 
Psyche 
[October 
The genitalia of the male are usually accepted as being the 
final criteria for species about whose validity there is any doubt. 
A study of the genitalia will also show the degree of relationship 
between species in a group. With these facts in view the present 
study was undertaken in the hope that significant variations 
might be found in the cedagus of species having only slight ex- 
ternal differences. 
Since it is very easy to make erroneous determinations in 
this group, the present paper includes only that material which 
was compared with the types. All the species were described by 
Lecont except five, and the specimens were carefully compared 
with the Leconte types in the Museum of Comparative Zoology 
at Cambridge. The other five species were identified by Le- 
conte, and were included in his collection. As my identifications 
agree with his, I felt safe in using these species in my investiga- 
tion. 
I wish here to thank Mr. Nathan Banks for his kind gene- 
rosity in allowing me the use of the collection in the Museum of 
Comparative Zoology. I am also greatly indebted to Mr. C. A. 
Frost who loaned me his collection with permission to dissect 
any of the specimens which I might see fit to use for such pur- 
poses. 
In a previous paper (Wilson 1926) the structure of the 
Coccinellid cedagus was described in detail. The general struc- 
ture of the cedagus of Scymnus is similar to that of other Coc- 
cinellids. The basal lobe surrounds the median lobe and is very 
variable in shape. In such forms as Scymnus americanus Muls., 
the basal lobe is quite similar to that of Brachyacantha ursina 
Fab., which is one of the simplest of the forms described in that 
paper. 
The material here presented seems to fall naturally into 
four groups, and if a study of the whole genus could be made it 
would probably be possible to separate the genus into several 
groups, each group showing some relation to the other groups. 
The oedagus of quadritceniatus Lee. is particularly interest- 
ing because the proximal end of the median lobe is not flattened 
and expanded as in the other species. The median lobe is also 
