506 Memoirs on the Coleoptera 



tribes of this work; if narrow in body and elongate-oval, the genus 

 may form part of the Ambatini (p. 3) ; if broad and strongly 

 rhomboidal, it is probably one of the Optatini (p. 20) ; if somewhat 

 ventricose, small to minute in size and with relatively small pro- 

 thorax, it is to be looked for among the Cyrionichini (p. 10) ; but 

 there are exceptions which may be puzzling, as shown in the generic 

 tables of these tribes; the body is apt to be conspicuously clothed 

 in all of them, the pygidium invariably covered by the elytra and 

 in none is the prosternum armed before the coxae. If the coxae are 

 moderately separated, the pygidium entirely concealed and the 

 beak more or less slender — to which however there are many 

 exceptions — the genus sought for will belong to the Coleomerini 

 (p. 84) if the beak be received in repose in a closely fitting sternal 

 channel, with the body oblong-oval, shining and glabrous or nearly 

 so, or to the Ccelonertini (p. 94) if the beak be somewhat similarly 

 sheltered in a shorter sternal channel, the body subcylindric and 

 variably clothed. If, with similar coxae and covered pygidium, the 

 beak should be. free, the genus may belong to the Diorymerini 

 (p. 31), if the upper contour of the body viewed in profile be 

 subsemicircular and the integuments smooth and glabrous — the 

 prosternum always unarmed, or to the Centrinini (p. 101) if the 

 upper contour be moderately arcuate and the body rhomboidal, or 

 to the Limnobarini (p. 269) if structurally as in the Centrinini, but 

 with narrower or parallel body; in both the Centrinini and Limno- 

 barini prosternal spines are often evident or conspicuous in the male. 

 If with widely separated anterior coxae — sometimes narrowly how- 

 ever — the sterna form an almost uninterrupted surface antero- 

 posteriorly, it is probably one of the Madarini (p. 323), which may 

 have exposed or concealed pygidium and occasional prosternal 

 spines in the male. If the pygidium be exposed and vertical or 

 nearly so, with the sternal surfaces interrupted in continuity, the 

 genus should be sought among the Barini (p. 429). There are some 

 other small special tribes which may include the genus in hand, 

 and, as to these, if the body be glabrous, rhomboidal and of brilliant 

 metallic color, consult the Eurhinini (p. 417); if very long, parallel 

 and more or less depressed, the Madopterini (p. 492) ; or, if it have 

 a large exposed and very oblique pygidium, narrowly separated 

 coxae, discontinuous sterna, slender rhomboid-oval body and elon- 

 gate slender beak, it may pertain to the genus Sonnetius (p. 321). 



