2 
Psyche 
[March 
the male here described was designated as the allotype of 
Notiothauma reedi, McL. 
The greater portion of the abdomen of the male of 
Notiothauma is of a castaneous color, but segments eight 
and nine (see fig. 1), and the gonopods labelled cx and st 
in fig. 1, are somewhat fulvous hued. The abdomen is rather 
broad and is somewhat flattened, and does not taper as the 
abdomen does in the Panorpidse (sensu stricto) , being 
more like the abdomen in the closely related family Mero- 
pidse in this respect, although the genitalia are much more 
primitive than those of Merope (which are elongated and 
rather highly specialized), and the genitalia of Notiothauma 
might readily serve as the archetype of the genitalia of the 
Panorpidse. On the other hand, the abdominal structures 
of Notiothauma present some remarkable modifications, 
which, with the general archaic character of Notiothauma , 
make it the most interesting and striking representative 
of the Mecoptera. Starting with the structures of the third 
abdominal segment and taking up the structures of the 
following segments in turn, I shall briefly describe the 
striking features of the abdomen, and point out wherein 
the structures of Notiothauma may serve as the starting 
point for tracing the evolutionary developments occurring 
in the other Mecopterous families. 
In the posterior region of the third abdominal tergite 
of the male of Notiothauma there occurs a median unpaired 
structure labelled n in figs. 1 and 5, which, for the sake of 
convenience, may be referred to as the notorganus or notal 
organ. A conical median tergal structure labelled po in 
figs. 1 and 5, borne on the following (i. e., the fourth) ter- 
gite, abuts against the notorgan n, on the third tergite. I 
have followed Felt, 1896 (Kept. N. Y. State Entomologist 
for 1894, p. 463) in regarding the notorgan n as an alluring 
organ which gives out an exudate licked up by the female 
prior to mating. The notorgan n (and the posterior struc- 
ture po) is not developed in other primitive Mecoptera such 
as Merope , Chorista and Panorpodes, (and it is likewise 
absent in the Bittacidse, Nannochoristidse and Boreidse), 
so that Notiothauma furnishes the only starting point for 
tracing the development of these structures in the Pan- 
