,( Ixxvi ) 

 plate is not so .sharply limited us it appears (" he in (be tigures. It does not 

 bear any spines. 



The second type is represented by PI. LXIII. f. 5 and 6. The membrane 

 connecting the steniite (vii. v) with the tergite (vii. is very small ; the 

 sternite is not membranaceous apically, the strongly chitinised plate e.xtending 

 right to the apex. The plate varies in form and size, occupying sometimes 

 the whole ventral side of the segment, the tergite being scarcely visible in a 

 ventral asjiect of the nbdonien (f (i) ; or it is smnller, trai)eziform, the tergite 

 encroaching npou the ventral side (f 5). The apex of the sternite is either 

 totally spinose (Sfxirr, Cejjiioiiodes, etc.), or at least spinose laterally {Faclii/gonia). 

 This type is a derivation from the first. 



The seventh sternite of the male of Sphimjidae is normal, being similar to 

 that of the sixth. The eighth sternite, however, is modified ; it is always 

 without spines, deejily sinuate as a rnle, and occasionally incrassate mesially or 

 produced into a process (PI. XXII. f 18—2'.)). In the Sesiinae and Philampelinae 

 with a stumpy abdomen {Scsia, Pacln/i/oiiia, }[afro(ilossttm, etc.) it is very short. 

 The eighth tergite of the male is s]iiiiosc. It varies in size and shape like the 

 seventh. It is long, and ajipears conical in dorsal aspect in Aclierontiinae, for 

 instance, and short and flat in .Uacfog/ogsum, Se.<i/a, and allies. 



The abdomen taken as a whole is mostly elongate-conical. Deviations from 

 this form, which represents the generalised type, are numerous. We mention 

 that the abdomen is ovate in some ffaemonliagia, flat and broad in Ilypaednlia, 

 broad and stumpy in Pdclti/gonia ; that it is horizontal in most spccie-i, and 

 curved upwards in many Amhidiciiiue and some Ac/ieront/imie. 



The scaling of the posterior segments exhibits sometimes striking features. 

 The scales at the ventral apical angles are occasionally i)rolonged to tufts (many 

 Scsiiwie and PhilampeliiKie : ().cy<tmhiili/.r : I'oliana : etc.). The long scales of 

 the seventh and eighth segments form tufts especially liable to modifications. 

 In Paclii/yonia the abdomen is triangularly truncate with a short lateral tuft; 

 this tuft is prolonged in Iliimintoidi'i^, the "tail" appearing divided. The 

 expansible fan-tail found in numerous Sexiinae and Nephelicae is generally 

 tripartite ; it occurs also in C'/pu iind allies, of the subfamily Amhulicinae. 

 The modification in the skeleton of the fan-tail segments consists in the plates 

 being short and amjjly movable. There is no additional division of the 

 segments besides the separation into a tergal and a sternal plate. We have 

 not studied the muscular apparatus. 



The modifications of the scaling of the abdomen are very instructive. The 

 upper scales are generally elongate, more or less hair-like in appearance, and 

 the underscales large, multidentate. Among the Spliimjidae asenanoj>korae we 

 find a good number of forms which have instead of the broad underscales long 

 hair-like ones, which are often modified into lanceolate spines resembling the 

 weak spines at the a])ices of the segments in the respective s])ccies. Kellogg 

 drew the conclusion, from his studies of the scales of Lcpidoj)tera, that the 

 hair-like scales represented an older type than the broad multidentate scales. 



