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LXXXV. PACHYSPHINX gen. iiov.— Typiis : moth'st,,. 



f^iiHi-liilhus, Harris {110,1 Litreille, 180-.'), in Sillim.. Journ. Sci. Art xxxvi. p. 202 (1H36). 

 LiKilhue, Grote {mm Fabricius, 1807), BuU. Buff,,!,, Soc. N. Sci. i. p. 24 (1874). 

 Aninrpha. id., he. ii. p. 227 (1874) {tinm. >iiid.). 



T,-ijil<iii<'i>, Butler, Tiaiix. Ziml. Siii\ Lntiil, ix. p. ,58il (1877) {,,0111. nuil. ; partim). 

 Mui-umlia, Kirby {mm Moore, 1882), Cat. Lep. Hit. i. p. 708 ( 18112). 



c??. Very close to Sp/i?nx, from, which it differs, in the larval state, in the 

 rednced horn, the slightly humped thoracical segments and less triangular head ; in 

 the iviacjo state, in the bristles of tlie jiilifer being mostly modified to liair-scales. 

 The abdominal tergites are sjiinose all over, the spines as stout as in Amorpha, le«s 

 weak than in Sphinx. Anterior tibia ending in a heavy thorn, homologous to 

 that of Sphinx orcUata, rcrisjii, and hinih'vmunni. Frenulum vestigial in both 

 sexes. 



$. Tenth abdominal sternite broader than in Sphinx. Clasper very broad, 

 very obtuse, the end of the abdomen a])]iearing truncate ; har]ie with two distal 

 lobes corresjionding to those of Amorpha, and an upper dentate ridge. Penis- 

 sheath without external armature ; a conical tooth upon the membrane of the duct 

 inside the sheath. No retinaculum. 



? . Vaginal plate with a low thick ridge before the vaginal cavity, without 

 lobes ; the whole eighth segment strongly chitinised. 



Larva granulose ; head more triangular in the last and in the first stages 

 than in the intermediate ones ; horn very short, longer in the young Inrva ; 

 thoracic tergites transversely raised, the crest also more prominent in the younger 

 caterjiillar. — Food-plants: Populus; Salix. 



Pnpa similar to those of Amorpha and Sphinx. 



Hah. Nearctic Region, from Canada to Mexico, westward to the Pacific. 

 Only one species, which is individnally, seasonally, and geographically variable. 

 Butler put this insect (in 1877) into a genus comprising the Old World species 

 allied to dip-as, and maintained that " this is unquestionably the proper place for this 

 species." Grote accepted Butler's opinion as being well founded ; and since then 

 numerous writers have followed in the same wake. However, the affinity of 

 moflestn with dt/ras and allies is very distant. Apart from structure, which was not 

 known to Bntler and Grote, and most likely not to any of the authors who were 

 misled by them, and therefore may be passed over, any casual observer who is 

 acquainted with the various species of Sphinx, Amorpha, and Butler's Triptof/on 

 (called by Moore ^farnmha, and dealt with in this Revisif>n under that name) can 

 scarcely fail to notice the close agreement in colour and pattern between Pachy- 

 sphinx, tSphinx, and Amorpha, and the conspicuous dissimilarity of Mariimha, the 

 species of which have all, on tlie forewing, the peculiarly curved, almost looped, 

 discal lines. 



Pachysphinx is to a certain extent a combination of Amorphi and Sphinx. 

 The thorax is unicolorous (or practically so) as in Amorpha ; the hindwing is red as 

 in Sphinx, and has the same anal patch as Sphinx hindermanni ; the forewing 

 agrees decidedly better with that of Amorpha. There are on the forewing of 

 Amorpha, in the middle area, five lines : two between the base of M- and the end 

 of the cell, the more proximal line forming the border of the dark band, the second 

 line being situated within the band and disappearing often ; beyond the cell there 

 are three more lines, the first obscure, often absent, the second more or less crenate 



