Malacoderm Genera Prionocerus and Idgia. 327 
upper posterior tibial spur is longer than the lower one. 
I, flavirostris and one or two others have the tarsal claws 
widened to near the middle, instead of at the extreme base 
only, but there is no trace of a membranous lobe in any of 
these insects. ‘he numerous testaceous forms with the 
head in part or entirely, and the apices of the elytra, black 
have given me the greatest difficulty in distinguishing the 
species ; and it has been found impossible in some cases to 
separate them at all satisfactorily till the ¢-genital armature, 
or the sixth ventral segment, has been examined. These 
structures have been dissected in nearly all the species of 
which the males are represented in the collections before 
me *, The tegmen (sensu Sharp and Muir) is furnished 
with two elongate, digitiform or spoon-shaped lobes, convex 
and almost smooth above, concave beneath, together forming 
an open tube, the lower outer edge of each (lateral) lobe 
being more or less ciliate or finely denticulate, and some- 
times sinuate or emarginate before the tip. The median 
lobe + (=penis-sheath or edeagus of some authors) consists 
of a long, acuminate tube, usually curved downward at the 
tip, but peculiarly shaped in the two Arabian forms here 
described (ef. Pl. XI. figs.9a and 10a), the opening from 
which the membranous sac or intromittent organ is extruded 
being placed on the dorsal aspect at some distance before 
the tip. The sixth ventral segment is normally triangularly 
emarginate in ¢, but in one species at least (cf. Pl. XII. 
fig. 49 a) it is so deeply bi-excised as to appear trilobed. 
One or two species have the sutural angle of the elytra 
strongly hooked or dentiform (cf. Pl. XII. fig. 50), a character 
peculiar to the @, as in the American genus Astylus. 
Figures of the g-armature of nearly all the species here 
enumerated are given on the accompanying Plates. 
The “ Prionocérides,” forming a subtribe of the ‘ Mely- 
rides” of Lacordaire based upon Prionocerus and Idgia, 
should be treated as a separate group or family of the 
Malacodermata, distinguished by the emarginate eyes, the 
single spur to the anterior tibiz, the simple tarsi and claws 
(the latter at most widened in their basal half), the more or 
less curved or excavate eleventh antennal joint, and the 
closely pectinate tarsal joints 1-3 of the male. 
* They have all been made by Mr. A. Cant. 
+ Cf. Sharp and Muir, Trans. Ent. Soc. Lond. 1912 and 1918. The 
term “ penis-sheath ” has been used by me for this organ in a recently 
published paper on the genus Astylus. 
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