299 



females and the abdomen is quite differently shaped and coloured 

 than in the opposite sex, but of the same species we find gynaeco- 

 morphous maies with the antennae of the same length as in the 

 temales and the abdomen structured and coloured as in the females ; 

 the maie génital segments in both forms are identical. It would be 

 of great interest to know if the internai maie génital organs are 

 developed in the gynaec'omorphous maies, but this question can be 

 cleared up oui y by entomologists disposing of material preserved 

 in alcohol. 



The colour-variability in some species and the inconstancy in the 

 forming of certain plastic characters in other species seem to 

 indicate that the Colobathristidœ are of coinparatively late geological 

 origin and they hâve probably corne into existence after the sub- 

 mersion of the land-bridge between northern South America and 

 Africa, but before the land-connection between New Guinea and 

 Soûl h America was sunken. 



The maps appended to the end of this paper will give a survey 

 of the geographical distribution of the Colobathristidœ, displaying 

 the number of species represented in the several countries and 

 islands. 



Molybditis nov. gen. 

 (ixolvfidiTiç = like lead) 



Corpus robustum. Gaput vix exsertum, e supero visum ante ocu- 

 los breviter triangulariter productum, e latere visum ante antennas 

 leviter rotnndatum et fortiter déclive sed non verticale, altitudini 

 basali subaeque longum, lateribus haud carinatis, vertice inter ocel- 

 los snlco brevi profundo ante ocellos vix producto et utrinque mox 

 extra et pone ocellum puncto transverso profundo instructo, gula 

 horizontali, oculis sessilibus, ab apice pronoti parum remotis, ocel- 

 lis majusculis, a basi capitis paullo remotis, ab oculis quam inter se 

 paullo longius distantibus, rostro coxas médias paullum superante, 

 articulo primo apicem prosterni paullulum superante, quarto tertio 

 paullo longiore. Pronotum antrorsum fortiter déclive et modice 

 angustatum, basi capite saltem 1/3 latius, lateribus ante médium 

 leviter sinuatis, impressione transversa parum profunda, lobo pos- 

 tico antico circiter duplo longiore. Margo posticus propleurae late 

 leviter bisinuatus. Scutelluin medio transversim elevatum, apice 

 sj)ina longa suberecta armatum. Hemelytra abdoinine angustiora 

 ($), corio area anteapicali triangulari aequilatera majuscula haud 

 coriacea instructo, venis corii crassiusculis, venis membrana? di- 

 stinctis, extima ante médium furcata. Abdomen ($) segmento primo 

 lateribus parallelum, deinde usque ad apicem segmenti tertii sensim 



