1(3() Tnlieritcmce and Evolution in Orilioptero 1 



examined microscopically. The examination of the section through the 

 pronotum of nigronotatus (/), about midway between the deep black 

 spot and the posterior end of the pronotum, reveals a deeply pigmented 

 hypodermis with the cuticle somewhat brown in places (Fig. 3, 7). 

 The examination of a sfection of leuconotus {B) from approximately the 

 same location as the one taken from nigronotatus (/) (Fig. 3, E) shows 

 the hypodermis to be practically without pigment and the cuticle 

 colourless. A section from approximately the .same part of the prono- 

 tum of leuconotus-nigronotatus (^7) (Fig. 3, BI) reveals a nearly clear 

 cuticle with about one-half as much hypodernial pigment as is found 

 in nigronotatus (/). The situation regarding pigmentation in the pro- 

 notum of texanus and the hybrid from it and leuconotus {B) appears 

 to be exactly the same as that for nigronotatus (7), leuconotus (5) 

 and their hybrid leuconotus-nigronotatus {Bl). In the figure (Fig. 3) 

 texanus is placed opposite nigronotatus, and the leuconotus-texanus 

 hybrid is placed opposite the leuconotus-nigronotatus {BI) hybrid, 

 although the drawings were made from the specimens first described. 



This study reveals the fact that the character of nigi-onotatus (7) is 

 as much present in this posterior part of the pronotum of the hybrid 

 leuconotus-nigronotatTjs {BI), as the more advantageously displayed 

 leuconotus {B), though the latter when the hybrid is scrutinized super- 

 ficially, is the only one apparent. The same pi'oportions and relations 

 in the pigmentation of texanus and the heterozygote, leuconotus- 

 texanus, are shown. The preliminary examination of the pronota of 

 some of the other hybrids and their parent forms reveals a similar 

 situation. The evidence indicates that the 23eculiar pigmental elements 

 of each of the patterns of the pronota of the parents are present in the 

 pronotum of their hybrid in about ecpial proportions. 



VI. Discussion. 



(1) r//e inheritance of the colour patterns. The inheritance be- 

 haviour throughout the experiments, with five exceptions (leuconotus- 

 luteolineatus-nigronotatus {BEI ) Table III (e)), and four others now 

 being bred and to bo described later, fulfils very nearly the Mendelian 

 expectations. Among more than 5000 recorded individuals resulting 

 from the crossing of species, inbreeding and crossing of hybrids, and 

 the crossing of hybrids with species, and more than 2000 recorded 

 progeny from the inbreeding of species, only the five unexpected 



