CORYLOPHIDA. 1038 
geniculate ; the two basal joints large, the first generally recurved ; the intermediate joints small and short, 
the last but one often larger than the rest; the three terminal joints always forming a much incrassated 
club; when not in use these organs are received into a deep groove which passes round the outer margin 
of the eye and extends with an outward curve into the prothorax. Palpi: mawillary large, 4-jointed, with 
the second joint much larger than the rest, and the fourth generally long and conical ; labial 3-jointed, 
with the second joint very large and often turgidly incrassate, the apical joint either acicular or rounded, 
or abruptly truncate. Mawilla unilobed, the lobe long and robust and usually armed at the apex with 
many long and very sharp teeth; in Rhypobius alone simple. Mandibles variable in form, generally armed 
at the apex with many long and very sharp teeth; in Rhypobius long and very slender, deeply bifid at the 
apex. Mentwm quadrate or oblong. Labium oblong, sometimes much elongate. Lingua variable in form. 
Labrum generally small; rounded, or emarginate in front. Head below, in Sacium and Arthrolips, very 
small and very narrow and with very small eyes; in all other genera transverse, with the gular region 
convex and the organs of the mouth very prominent, and the eyes often large and very conspicuous. 
Prosternum usually short, much elevated between the coxe, and prolonged and dilated posteriorly ; epimera 
generally very large, enclosing the coxal cavities in many genera. Mesosternum usually large; episterna and 
epimera large, the latter, except in Micréum and Conodes, not extending to the cavities. Metasternum 
moderate, not extending to the sides of the body; episterna and epimera broad and very long. Venter 
composed of five or six segments; the basal segment very large, nearly as long as the others combined ; 
the apical segment simple (at least in the Central-American genera). Legs sometimes long and slender, 
usually simple; in Orthoperus the anterior tibis are often very long and much incurved; tarsi 4-jointed, 
the three basal joints short, the third joint often very small, the terminal joint elongate; the claws either 
long and slender, and faintly curved, sometimes convergent anteriorly, or robust, strongly hooked, and 
denticulate on the lower edge. 
The whole Family may be divided by superficial characters into the following four 
Tribes, viz. :— 
Posterior angles of the thorax produced . . . . . . Sericoderina. 
Posterior angles of the thorax not produced. 
Form elongate... .. .. . . . . . . Saciina. 
Form rounded. 
Head wholly concealed . . . . «. . . . « Corylophina.. 
Head partly exposed . . 2. . . . .).)SC)SOCOrthoperina. 
The division of Families into Tribes is purely artificial, of no real scientific importance, 
but useful as a help towards the harmonious arrangement of form, and as affording to 
the mind some idea of the general appearance of a genus previously unknown. But it 
appears to me that this division, if carried too far, would become perplexing and unne- 
cessary. The four new genera described in the following pages form a striking illus- 
tration of the point in question. These genera differ equally from any of the Tribes 
above mentioned, and from each other. In this case, if strict definition was imperative, 
each would demand a separate Tribe to contain itself, and itself alone. If hereafter 
other genera be discovered bearing close affinity to either of these, their generic characters 
might then assume a divisional importance, and justify the creation of a fresh Tribe. 
But for the present it will be more expedient to place Conodes and Ectinocephalus 
with the ‘Saciina’ (although in each the head is more or less exserted beyond the 
thorax), and Microum with the ‘ Corylophina.’ 
