MORPHOLOGY OF THE LEPIDOPTERA. 153 



views of Pieris and Sphinx on PI. XV. figs. 3 and 14. The homology of the anal 

 valve and cremaster was discovered by myself in 1876, but was not published till 1888 

 ('Forms of Animal Life,' edit. 2, p. 153). Mr. Poulton has confirmed the homology by 

 the presence of a peculiar streak of colour in Aglia tau (Trans. Entom. Soc. 1888, 

 p. 566). But I have found lately that Riley gave the same homology in his paper "On 

 the Philosophy of Pupation " ('American Entomologist,' iii. 1880, p. 162). Kunckel, 

 however, in a brief account published in the ' Comptes Rendus,' xci. 1880, pp. 395-397, 

 just after the appearance of Riley's paper, stated that the cremaster was made by the 

 fusion of the anal prolegs. The truth of Riley's view is proved by PL XV. fig. 18, where 

 the ci'emaster is drawn as displayed by dissection within the anal valve of the larva. 

 The terms sustentor ridges and sustentors are proposed by Riley in the paper just quoted. 

 He homologizes the sustentors with the soles or " plantse " of the anal prclegs, the 

 sustentor ridges with their limbs. In this homology I believe him to be wrong. The 

 sustentor ridges and sustentors are probably peculiar developments of the body of the 

 tenth somite, found only in some Lepidoptera. The eminences on either side the anal 

 furrow (PL XV. figs, 1, 4, 8, 11, r.p.), or rectal prominences, as they are termed by 

 Riley, represent the prolegs. To this point I hope to return in my next contribution, 

 and will only add here that the anus of the chrysalis lies just below the base of the 

 cremaster, at the dorsal end of a long anal furrow which represents the furrow or 

 depression between the two anal prolegs of the caterpillar. 



The abdomen of the imago (PL XVI. fig. 24), as compared with the abdomen of 

 both caterpillar and pupa, is not only less in size and bulk, but it appears also to consist 

 of only nine somites, the number usually assigned to it. The first somite is short, its 

 sternum fused to that of the second sumite; its tergum is composed of a middle lobe, 

 de Lacaze-Duthiers' lamella (p. 151, ante), and of two lateral lobes ; its spiracle (sp.) is 

 hidden at the bottom of a deep recess *. 



The following six somites (2-7) with their spiracles are quite distinct, but the seventh 

 sternum is fused to the eighth, as is more clearly figured in PL XVI. fig. 25. The 

 eighth somite (8) has a distinct tergum and sternum, the latter containing the orifice of 

 the bursa copulatrix (PL XVI. fig. 25, a.b.c). Its spiracles are lost; indeed the 

 atrophy of the trachea? which originates from the abortive eighth spiracles of the pupa 

 is nearly complete by the 4th or 5th day of pupal life in Vanessa Io. In a male imago 

 of Sphinx ligustri I have seen slight scars indicating their position. 



There remains the anal cone or papilla (t a.p., PI. XVI. fig. 25), which contains 

 the oviducal aperture as well as the anus, and is usually denominated the ninth 

 somite. I shall show further on (pp. 166-7, PI. XIX. figs. 73, 75, 77, 78) that when the 

 oviducal aperture shifts backward till it is close beneath the anus, an ingrowth or fold of 

 hypoderaiis takes place surrounding the anus, oviducal aperture, and odoriferous glands. 

 This fold corresponds to a small portion only of the tenth somite, i. e. to the anal area. 

 Consequently I believe that it is more correct to maintain, at least with reference to 



* The peculiar conformation of the tergum of the first somite is, I believe, due to the presence of strong bundles 

 of muscles which arise from its middle lobe and pass into the thorax. The existence of the spiracles of ihis somite 

 in the spot indicated was verified by dissection. 



24* 



