( Isxii ) 



occur ill AclnriiidiiiKic. ami is raivlv met with in Chocrocampium {Fhaiio.rijla 

 lii/strijc) ; among the other subfamilies this fonu of wing is often fouud. The 

 lobe at R' is generally the most jirominent ; but this rule does not hold good 

 in every case— in Piseiuleiii/o, for instance, there is no distinct lobe at R^ but 

 a prominent lobe at R'. 



The hindwing is scarcely less variable within the family than the forewing. 

 The apical angle, the point farthest from tiie base, lies at .SM= or (rarely) 

 at R' ; the anal angle at !SM-'. The distal margin is less irregular than that of 

 the forewing in the lobate speeies-as a rule convex, sinuate before anal angle 

 or not; the ajjcx is very often completely rounded (PI. I. f. 5. (i. S. 10 11. 12). 

 The costal margin, ordinarily straight proximally and sliglitly convex distally, 

 undergoes very conspicuous modifications. It is dilated into a proximal lobe 

 {Macioylo»xum aquila : (:i(jrinteop<djji(s ; Alciiroii) ; or the costal area before 

 vein C is widened and, when the insect is at rest, overlaps the forewing, 

 recurving and enveloping tlie costal margin of the latter {Stoluloptera and 

 lhi})(ii'dnUa) ; or the costal margin is dilated distally, and either sinuate 

 proximally of the lobe or not {Deymaptera) ; or it is dilated proximally and 

 distally and sinnate between the lobes {Giirelca). 



Though the opinion to which Butler gave expression iu 1875, that an 

 obvious diii'erence in the shape of the wing is a generic difference in this 

 family, is not correct in its entirety, the wings of close allies and of the sexes 

 being sometimes very different (PI. 1. f. 1, c? ; 2, ?), a special wing-form is, 

 however, in many cases accompanied by other distinguishing characters, and 

 restricted with these to an assemblage of allied species constituting a genus. 

 In such cases the shape of the wing is a very convenient character to recognise 

 n genus by, or to be used in a key. Protambulyx (PI. I. f. 3) and Oxijambulyx 

 (PI. I. f. 2) illustrate this point, all the species of the former genus and 

 its close ally Amplyptei'us, which two genera are purely American, having the 

 apex of the forewing truncate-sinuate, while all the species of the purely 

 Oriental genus Oxijamhtdyx have the apex acute. Oxyambulyx and Protambulyx 

 can, therefore, easily be distinguished by the shape of the wing. However, 

 this distinction alone would not justify us in treating the insects referred to as 

 generically different ; the justification lies in the whole organisation of the 

 species proving them to belong to two sharjily defined groups, each containing 

 material which is inter se more closely related than with the members of the 

 other group. 



The abdomen of Lepidoptera is composed of ten segments. The ninth and 

 tenth of the S and the eighth to tenth of the ? are modified, so that the last 

 one of ordinary appearance — the last of descriptive Lepidopterology — is the 

 eighth in the S and the seventh in the ? . The first segment is short and 

 generally overlooked in ordinary descriptive work ; it has no free sternite, and 

 the tergite lies often close against the thorax (PL LXIII. f. 1. 2). 



The base of the abdomen of a number of families of Moths exhibits very 

 distinctive features, here being found organs of various kinds, most likely all 



