( Ixxx ) 



olasj.er (I'l. XXX II I. f. I. 14 ; I'l. XXXIV. f. G). In liy far the greater mimber 

 of species tlie liarj)e is siiorter tiiaii tlie clasper. A dense patch of scales is 

 found on tlie harj'c of nearly all Protoparce and in many other Acherontiinae. 



The right and left clasper and harpe arc generally the same in ontlinc and 

 structnre. However, there are exceptions, asymmetrical development occurring 

 also in these organs, as will be detailed below. 



The external jilate of the clasper is divided by a longitudinal rib-like 

 incrassation into a narrow dorsal and a large ventral portion. The dorsal part 

 is generally concave above the rib. Ui>on and near the rib there is a peculiar 

 modification of the scaling found in a great number of Splnngidae. We 

 consider it an organ of friction, by means of which a sound of some kind is 

 produced. ^Ve do not know whether a similar organ occurs anywhere else 

 among Lepidoptera. There are two types of tliis organ, the one contined to 

 the Spliiiu/idae ast'ma)iojthorae, the other to the Spldnyidae semanophorae. 



In the former group of Splnngidae it is a patch of scales lying more or 

 less flat upon the clasper (PI. LVIII. f. 29—32). The patch as well as the 

 scales vary in the different species (respectively genera) in shape and size. 

 The patch is as a rule restricted — being, for instance, narrowly halfmoon-shaped 

 in Protamhulyx strigilis (PI. LVIII. f. 3(1), triangular in Protambuh/x euri/alus 

 (PI. LVIII. f. 32). But in some cases it is very large^Ampli/pterus (PI. LVIII. 

 f. 29). The scales of the patch are rounded and entire, or elongate and dentate 

 (PI. LVIII. f 35) ; the middle ones are half erect in Poliana bachholzi and 

 micru. A peculiar modification obtains in Polyptijclnis trisecta and P. ortho- 

 graplms (pp. 243. 244). Here the scales are obliterated for the greater part, 

 the dorsal area of the clasper being naked and rough with some grannies. 



The friction-organ of the Splnngidae semanophorue consists of lanceolate 

 scales which are half erect. The scales are very numerous and small 

 (PI. LVIII. f. 3G), or are reduced in number and have increased in size 

 (PI. LVIII. f. 37), the smallest number, namely one, being found in Ilippotion 

 rebeli and isis. The scales are strongly striped, have generally a prominent 

 midrib, and are more or less obviously asymmetrical (PI. LVIII. f. 38) ; they 

 are more often truncate than pointed. In Ort/ba kudeni (PI. XLVI. f. 4) 

 the organ is entirely diftVrent, consisting of a large mass of long, wire-like, 

 brittle hairs. 



Among the Ambulicinae with friction-patch on the clasper we find a number 

 of species which possess a corresponding organ of scales on the inner side of 

 the eighth tergite. This organ is almost confined to the Ambulicinae, being 

 found elsewhere only in some Acherontiinae, not in any Splnngidae semanophorae. 

 The organ consists of one single row of large scales, or of several rows. The 

 scales are ribbed, and are so closely applied to each other, or are even soldered 

 together, that they form a kind of ribbon at the apical and lateral. edge of the 

 tergite, the flat ends of the ribbon being directed towards the clasper. This 

 ribbon is either continuous from one side to the other (PI. LIX. f. 1), or it is 

 interrapted apically (PI. LVIII. f. 39. 40 ; PI. LIX. f. 2). The scales of the 



