42 Trans. Acad. Sci. of St. Louis. 
sensibly narrowing behind the eyes, so that they would seem 
to be almost subspecifically distinct, and, if seen in the ex- 
tremes alone, might be considered specifically different; I 
notice the same variability, however, in specimens of texanus 
taken at Galveston. — 
The two species anceps and vitatum * of Horn, —the only 
other members of the genus thus far described —are not repre- 
sented in the material before me, and I am therefore compelled 
to omit them from the table; the former seems allied to flori- 
danum and the latter to pimerianum, but differs from this as 
well as all other of our species in coloration, being testaceous 
with the last two abdominal segments black, the usual rule in 
bicolored species being to have the last two ventrals paler than 
the others. -Anceps is black, shining, with piceous abdomen, 
robust in form, with unusually large head, and, like vitatum, 
occurs in southern Arizona. Convergens is by no means 
identical with floridanum, as announced by Horn, the two 
species differing in the sexual modifications of the sixth ven- 
tral, the latter being singularly and exceptionally modified in 
floridanum as represented by New Jersey cotypes. 
In this genus there are only two really distinct kinds or 
classes of males and not three as stated by Horn. The first 
kind has the lobe of the third ventral present in more or less 
developed degree, and the second has no vestige of lobe but 
retains the discal marks as perfectly developed as the first. 
There is apparently no other differential character, though 
the two classes of males probably play quite different roles in 
the life history of the species. If the lobe gradually dimin- 
ished to complete disappearance, there would manifestly be 
but one class of males having a very variable appendage, but 
I have never seen an unlobed male presenting any trace of the 
lobe, and such traces would undoubtedly be seen occasionally 
if the lobe disappeared in that manner. We ure therefore 
led to the conclusion that there is only a certain amount of 
variability in the lobe and that the unlobed males must con- 
stitute a distinct class of that sex — possibly infertile. 
* The significance of this specific name is somewhat obscure. Its repe- 
tition several times would seem to show that it is not a misprint for 
vittatum. 
