No. 407.] A SINGULAR ARACHNID. 845 
So much for the description of the female of Kawnenia 
mirabilis. From this description a single specimen among 
my material differs so much that I am compelled to regard it 
either as the hitherto unknown male of Grassi's 
species or as an entirely new form. I choose the 
former alternative, since the differences are con- 
fined, so far as I am able to determine, to size, 
the structure of the genital valves, and the caudal 
flagellum. The specimen is only .5 mm. in 
length. The genital valves, seen in profile in 
Fig. 3, certainly have a very different shape 
from those of the female, although I am unable Ar 
to form a clear conception of their structure. The caudal flagel- 
lum, represented in Fig. 4, consists of only six joints of gradu- 
ally decreasing size. There are only six bristles in the larger 
circlet of each joint, and the smaller circlet 
of appressed bristles is present only on joints 
one to four. In addition to the larger bris- 
tles, joints three to six have a number of 
minute scattered hairs. Of course we may 
consider the possibility of an abbreviated 
regeneration of the easily broken caudal 
flagellum, both in this specimen and in the 
case of the two above-mentioned females, 
with eleven and fourteen joints respectively. 
I am certain, however, that this six-jointed 
flagellum cannot represent merely a young 
stage in the development of the fifteen-jointed 
flagellum of the female, for I have seen 
several young female specimens of about the 
same size (.5—7 mm.) with a large portion 
of the caudal filament, eight to ten joints, 
of the normal form. 
From the description of Koenenia we pass 
to a consideration of its affinities. Grassi 
established it as the type of a distinct arachnid order, which 
he designated as Microthelyphonida, a term somewhat lengthy, 
to be sure, but nevertheless suggesting the small size of the 
Fic. 4. 
