( Iviii ) 



ami iieiir allios,* but is iidt idciiticiil with it, occiii-s only in two species of 

 Aiitljulicinae, ciicli reiireseutiiig a genus of its own — namely, Monardd. and 

 Cirssoiiia. In tigs. 1 and 2 both kinds of Sphingid pectinations aie incipient. 

 If the doi-so-lateral expansion {dip) became prolonged, the result would be a 

 ])ectinated antenna of the first ty]ie ; if the subventral carinae {re) became 

 prolonged, we should have a ])ectinated antenna of the second type. The dorso- 

 lateral expansion is very rudimentary in Moiianln and Cressonia, and the nj)per 

 fascicles stand ajiart from it, having in a dorsal asfiect (PI. LXI. f. 5) the same 

 appearance as in ordinary fasciculated antennae, this being a special feature of 

 the Sphingid bipectiuated antenna. The asymmetry of the segment is distinct 

 in Hg. 4. 



As said above, the fasciculation, i)ectination, and the comi)ressed shape of 

 the antennae obtain in a much higher degree in the male than in the female ; 

 very often the female antenna is simjile where the male antenna is complex in 

 structure. Now, the question arises. Does the simple antenna really represent 

 the more ancestral state of development as maintained above, or is the simple 

 cylindrical segment derived from a more comi)licated segment in consequence 

 of the reduction or loss of the special structures ? Poulton, from researches on 

 the pupae of some Satuniiidue, came to the conclusion tlnxt the second alternative 

 was correct — namely, that the short-branched Saturniid female antenna was a 

 development by reduction from a longer-branched antenna. Though the con- 

 clusion was perhaps rather hasty, inasmuch as the fact was not taken into 

 account that the specialisations of the male are often trans[ilanted on to the 

 female, it was nevertheless suggestive, and served to draw the attention to a 

 neglected jioint. If one considers the case of the similarity in the sexes of 

 Uliopalopsiiclic by itself, one must come to a conclusion similar to that arrived 

 at by Poulton. For tiie absence of fasciculated ciliae from the male of Rhopalo- 

 pci/clio. cannot be exj)lained by assuming that this genus had preserved the 

 original sim]ile state of ciliation ; such an explanation seems to us to be almost 

 absurd, coufidering that Rlwpalopsi/che is in all otlier respects very specialised, 

 and is the only exception from the rule among all the Sphimjidae. And 

 therefore there remains only t!ie second alternative — that the male antenna of 

 Rhopalopsi/clie has lost the fasciculated ciliae, and thus become simple. If that 

 is true — and it cannot be seriously doubted, we think — one might conclude with 

 some degree of justification that the same line of development from the com- 

 plicated to the simjilified observed in this male obtaiued also in the female sex 

 of Sphinyidae ; that is to say, tiiat the sirajile female antenna of Sphingidae 

 was a derivation from a fasciculated female antenna. And it might further be 

 advance<l, as a confirmation of (lie evidence upon which that conclusion is based, 

 that there is a wide-spreiid tendency of retrogressive development in Sphingidae, 

 to which we shall liave to draw attention in many places of this Revision. 

 However, when we take into consideration the two types of pectinated antennae 

 found within the same subfamily of Sjdiinyidae {Ceridia, PI. LX. f. 27. 28 ; 



• Bmilb, Ent. Amcr. iii. p. 2 (1XK7); id., Trans. Aiiier. Ent. Soc. xv. p. 230 (1888). 



