134 MISSOURI BOTANICAL GARDEN. 
Pronuba synthetica (a); P. maculata (6); and Prodoxus 
decipiens (c), drawn to the same scale. In P. synthetica 
the receptaculum averages about 1. mm. in length and 0.66 
in width ; the crusher has a diameter of 0.43 mm., the longer 
rays about 0.17 mm. in length and the axis or hub about 
0.10 mm. in diameter. The crusher in this species looks 
much more like a burr, there being 16 of the longer, 24 
of a shorter size, 32 yet shorter and a number of the 
shortest which graduate into the tubercular inner surface of 
the hub. In P. maculata the receptaculum has a length of 
0.66 mm., and a diameter of 0.5 mm.; the crusher has a 
diameter of 0.4 mm., the longest rays a length of about 0.17 
mm., and the axis a diameter of 0.06 mm. In Prodoxus 
decipiens the receptaculum has a length of 0.65 mm. anda 
diameter of 0.8 mm. The crusher measures 0.09 mm. with 
the longest rays 0.05 in length and axis 0.02 in diameter. 
The axis is relatively longer than in the other species, and 
the spicules are much reduced in number. 
The object of these chitinous bodies has been somewhat 
of a puzzle, all the more difficult to solve that they seem 
to be quite exceptional, and, in the remarkable develop- 
ment which they here present, absolutely unique, so far as 
Ihave been able to ascertain. They attracted my attention 
in my earlier studies of Pronuba and I was glad to find, on 
visiting Dr. H. A. Hagen in 1880, that he had been very 
much interested, in his studies of Prodoxus, in the similar 
but smaller organs of that insect. His explanation of their 
function, as elaborated in the Zoologischer Anzeiger (Jan. 
1882), is doubtless correct, viz., that they serve to liberate 
the spermatozoa from the spermatophores, but he was in 
error in locating them in the bursa instead of the recep- 
taculum. The muscular arrangement which I have de- 
scribed is well suited to such a purpose. In the somewhat 
flattened receptaculum the spicular arms actually inter- 
mingle and the radiating muscular coat possesses the only 
arrangement of fibers which would enable a simple con- 
traction to bring at once the whole contents of the sac into 
