6^3 



The female has typically two fine linear depressions, one in the 

 eighth sternal region, the other in the ninth. They correspond to the 

 paired vesicles invaginated from the larval hypodermis (see infra) and 

 to the apertures of the bursa copulatrix and oviduct respectively in the 

 adult. In Pieris and Pontia they possess slightly raised oval margins. 

 In Vanessa a continuous line interrupts the eighth and ninth sterna. 

 This line indicates a shallow furrow at the bottom of which the two 

 apertures lie : and it appears to be continuous because the interseg- 

 mental membrane between the two somites is completely folded in- 

 wards instead of being superficial and smooth as in Pieris and Pontia. 

 In the Heterocera [Sphingidae, Hepialidae, Arctiidae, and Noctuidae) 

 examined . the ninth sternum has a triangular extension forwards, 

 invading the eighth sternal region and it is not clearly marked off 

 from the tenth somite behind. There are either the two typical linear 

 depressions, one in the eighth sternum, the other at the apex of the 

 triangular plate of the ninth sternum as in many Sphingidae: or what 

 is probably more common there is a single depression at or close to the 

 apex of the triangular plate of the ninth sternum which appears to 

 represent the two typical depressions confluent with one another. This 

 is the case in all specimens oî Sphinx ligustri that I have seen. But 

 there may be variations in the same species. Specimens of Cossus 

 ligniperda and Zeuzera aesculi may have two depressions or only one. 

 Every example of Cucullia verbasci that I have seen has but one depres- 

 sion : a single example of C. scrophulariae which has come under my 

 notice, has two. 



II. One of the great peculiarities of the Lepidoptera is the existence 

 in connection with the female reproductive organs of two separate ex- 

 ternal apertures — the aperture of the bursa copulatrix, and the aper- 

 ture of the oviduct. The former is ventral, the latter terminal, posterior 

 and immediately ventral to the anus on the same papilla. De Lacaze- 

 Duthiers in his researches on the genital armature of the Insecta 

 came to the conclusion I ) that the orifice of the bursa is in connection 

 with the seventh sternal region and is altogether secondary, whilst 2) 

 the oviducal aperture represents the genital opening of other female 

 Insects and, 3) that the somites usually intervening between the ovi- 

 ducal opening and the anus are absent in the Lepidoptera. See the 

 table on p. 230 of the Annales des Sc. Nat. (3) XIX, 1853. It is well 

 known, however, that the caterpillar has ten abdominal somites, the 

 first eight bearing spiracles, and the tenth the anal valve and two anal 

 prolegs. The ninth somite varies in the degree to which it is pronounced 

 externally, A chrysalis has the same number of abdominal somites, 



