4 Mrmutra of thr Imluni Mti»rum. [V<»L. VII, 



thi« arlilitiitiiiil |mir of niar({initl tul)cn-lrs in formed a<« a result of tbiH tendency. Solrtutryeius 

 is t<K) cKwIv hIIu*<I to /Vh/ij/«>^»»iji iind AVtmioMMM to iidniit of any dniilit an to the itlentity 

 of the huniulogie-i of their i-i*phiili<' tulM-rili's. Tin* <e|)hnhr tiiUTrlps of rprtain «.jK'<ie« of 

 theio however, bear the eloMcit |M>H.sil>li> n>M'nibliince tu tboMo of the Indo-AuKtralian 

 geniiH Lrfiiautajr ; ami there dt»e.H not np|>ear to \w any roncIu.sive evidence to ' Iicr 



the honiohtgies of l.t/ttaulaj are the Mime as thone itf Tanfuiintia. an previously .. or 



may not really Im> the same at* thost* of Knouotnut. In the former (-a^e the inner nnd outer 

 pairs of marginal tulM<r<les will he the tnie inner and outer tuljcreles re>i)ectively, and the 

 rudimentarv tuherrle^ sometimes forme<l on the frontal riiige.s at the p«iiiit where thetn- liend 

 forwardn will he scfonilary ?<tnu-ture.s. In the latter i-ase thes« nuliincntari* tnliorrle.s will 

 represent the true inner tulwrele**, the inner pair of marginal tub«>r«lf'.- will Im- th.- f hh- nutir 

 tubercles, and the outer pair of marginal tuberelcs will be seeondary structure 



It was suggestrti in my " Aecount of the Oriental I'avsjilidae " (p. ^^30) that the 1^-ptau- 

 lacinae were of comparatively recent origin, ami wert' still spreading from some di>tributional 

 centre towardM the middle of the Indo-Au»tralian area, into the outlying |?art.H of this 

 an-n. such as the Indian Peninsula ami Ceylon. If this is so — as all available evidence 

 n'«ar«ling their tlistribution seems to indicate it is most unlikely that they are at all 

 cli»sely relate<l t(» any but Indo-Australian groups, a siiggpstion wIiom- correctness is 

 contirme<l by the fact that the anterior lower t«M)th in the Lcptaulacinae is of a form found 

 only in Imlo-.Vustralian groups (see bolow. p. g). Presumably, therefore, the origin of 

 the I^-ptaulaciiiae is to be sought anions lndo-.\iistraliaii forms. Pait there is no definite 

 evidence to shtiw that they are in any way related to Taniuinius, the only known Ind(H> 

 Australian Pa^walid to which they bear even a superficial resemblance. The fact, moreover, 

 that in most Indo-.Vustralian forms the outer tul>ercle.s tend to be separate<l bv a distance 

 which is le.s.-i than the width of the ily|;eus. makes it easy to suppose that the evolution 

 of the l>eptaulacinae may have been on lines parallel to those of the evolution of Kthiopian 

 fomu. 



In view of tbi.H uncertainty as to the homologies of the cej)halic tubercles in the l^>ptau- 

 lacinae it seeiuii best to continue to u-se the terms " inner " and " outer " tubercles in the 

 connection in which they were usp<l in niy previous paper ; but in achlition to insert the 

 wonl ■• marginal," when speaking of the Leptaiilacinae, in «irder to show that in this co-se 

 the terms are u.setl in a des«Tiptive sense which is not necessjirily in accordance with 

 nioqdiology. 



Flii/hllfHn Sjteciea. 

 In JM'veral groups of American and Imlo-.Vustralian Passalidae there are s|)ecies whi«'h 

 ha^• habit of tliyht. This tends in all casps to priHluce certain modifications of 



-tn 



1. The union of tl.e lateral anil interiniHliate areas of the metasternum. 



2. The union of the elytra in the middle lino. 



;>. The shortening of the elytra and the rounding of all their contour*. 

 4. The r«>duction of the wings, which up|>ear t<i become thereby more efficient 

 stritlttlating organs. 



