616 THE AMERICAN NATURALIST. [VoL. XXXV. 
in its distribution. A young Danish zoólogist has recently 
. found in Siam a distinct species of Koenenia which Dr. Hansen 
is to describe. Dr. Silvestri, the discoverer of the species from 
Paraguay (K. grassii), has promised me a few of his specimens 
in return for the Texan species, which I hoped to have for com- 
parison before this paper was finished. I have likewise been 
unable to collect any K. parvula,! of which species Dr. Wheeler 
has found a single specimen, which he has briefly described 
in his paper (p. 233). When descriptions of these species are 
published a more correct idea can be framed of the valuable 
taxonomic characters of the hitherto unknown order. 
Koenenia wheeleri n. sp. 
I desire now to name our principal Texan form after its 
discoverer, Dr. Wheeler, and to give along with its internal 
structure a short description of the characteristics which set 
it apart as a new and distinct species. 
In the beginning I may say we have been more fortunate 
than Drs. Hansen and Sorensen in being able to distinguish 
the two sexes. It hardly seems possible that the males of 
Grassi’s species could be so rare when they are so abundant in 
our species. In fact, in the material collected in the fall, the 
males predominated. Very few females were to be had then, 
and those few were so small and insignificant that it was 
thought they were the males, The criterion taken for dis 
tinguishing the sexes in this material was the opaque glisten 
ing body in the second abdominal segment of the female, ag 
receptaculum seminis of Hansen. Unfortunately the seminal 
vesicles of the male are situated in the same region and have 
much the same appearance; hence Dr. Wheeler, in his inter 
esting paper, was misled into thinking that the male was F 
the other sex. It was not until fresh material was collected 
this spring and sections made that the mistake was discovered: 
In size and general form the sexes are alike, and it was pei 
after examining sections that one could say for the first we 
that the animal possessing the more complex reproduce” 
appendages is the male. 
1 I have the pleasure also of giving-this species its name 
