240 
[October 
group there are four species, and only four species, of which there are 
in existence nothing but unique specimens, viz.: melsenops^ Jcuy'ilw, 
adelphus and quadricolor n. sp. In all four cases these specimens are 
% S . Supposing no selection to be exercised, and supposing % and 9 
to be equally numerous, the chances are 15 to 1 against such an event 
happening, whence we may safely infer that the 9 9 in this group are 
not as numerous as h S . 
S 9 • The ground color is yellow, almost always tinged with 
green. 2nd. The labrum is immaculate, except a fuscous dot on its 
outside basal corner, and it has almost always an impressed median 
puncture^ the central lobe of the labium is obfuscated throughout. 
3r6?. The large yellow lateral spot at the back of the eyes is always 
conspicuous, and presents occasionally the appearance of 3, not 2 sub¬ 
confluent spots, but the three are almost always entirely confluent. 
Afh. “ The base’^ [i. e. the posterior prothoracic lobe] “ and the pos¬ 
terior BORDER of the prothorax yellow’’ (^Monogr. Goinphin. p. 126) 
is a manifest clerical or typographical error for anterior border”; 
i.e. anterior prothoracic lobe. The term “base” would include the 
“ posterior border.” hth. It is only occasionally that the humeral fus¬ 
cous stripe of the thoracic dorsum is confluent with the antehumeral. 
Qth. It is only in a single % that I can discover any vestige of the “ ex¬ 
ceedingly slender blackish pleural stripe” in the suture between the 
meso- and meta-thorax, which M. Selys calls “ the second suture,” and 
even in that S it is nothing but an irregular obfuscation.—The ante¬ 
rior dark stripe, which lies midway between the “second suture” and the 
humeral suture, is interrupted about halfway to the notum, but con¬ 
tinued again in a more or less obvious short stripe immediately under 
the front wing. 1th. In two % only out of seven there is a yellow dorsal 
vitta on joint 9 of the abdomen, wide in one, narrow in the other; and 
in the % that has this wide vitta on 9, and likewise in the 9 which has 
no vitta on 9, there is also a small median dorsal yellow spot on 10. 
These markings were described by Say, and traces of them were no¬ 
ticed by Mr. Selys in his 9 . Sth. The large, lateral, basal, yellow spot 
on abdominal joint 8 vaties somewhat in size, and always along its 
basal ^ attains the margin and occasionally along its whole length ; 
almost always, in addition to this basal spot, there is a submarginal 
terminal yellow dot or small spot on 8, with which in one % the large 
