152 DESCRIPTIONS OF PREPARATIONS. 



Serictaria. Helm, Z. W. Z. xxvi. 1876; Lidth van Jeude, Z. A. i. 1878; 

 Joseph, Z. A. iii. 1880. 



Nervous system. Newport, Ph. Tr. cxxii. 1832; cxxiv. 1834 (includes Vanessa 

 Urticae) ; Cattie, Z. W. Z. xxxv. 1880. 



Blood. E. B. Poulton, P. R. S. xxxviii. 1885. 



Protective coloration and markings. Poulton, op. cit. ; ibid. xl. 1886, and 

 Trans. Entomol. Soc. 1884 and 1885 ; Weismann, Studies in Theory of Descent 

 (translated by Meldola), London, 1880-82 ; Cameron, on Smerinthus, Trans. Ento- 

 mol. Soc., 1880. On colour, see also Hagen, Proc. American Acad. (2) ix. 1882 ; 

 F. Muller, Kosmos, xii. ; Wallace, Tropical Nature, London, 1878, pp. 158, 249. 



30. PUPA OF PRIVET HAWK MOTH (Sphinx Ligustri}. 



THERE are two forms of quiescent pupae among Insects : one in which 

 the antennae, mouth-parts, limbs and wings are free, the other in which they 

 are coherent to one another and to the body. Of the first kind of pupa 

 two varieties are distinguishable. In one the larval skin is simply thrown 

 off. It is known as incomplete, exarate or libera, and occurs in the Neuroptera, 

 Coleoptera, Hymenoptera and some Diptera. In the other variety, known as 

 coarctate, and occurring only in Strepsiptera and Diptera, the larval skin is 

 retained, and it either preserves the form of the larva, e. g. Strepsiptera, 

 Stratomyidae, or contracts into a barrel-shaped structure, e. g. Muscidae. 

 The second form of quiescent pupa, known as obtected, larvate, or signate, is 

 characteristic of Lepidoptera. The cohesion between the limbs, &c., as seen 

 here, is due to the hardening of a sticky fluid which covers the surface at 

 the moment when the caterpillar skin is thrown off. 



The obtected pupa is either angular, as in the majority of Lepidoptera 

 with club-shaped antennae (=Rkopalocera], and then often brightly tinted ; 

 or it is conical, as in Sphinx and other Lepidoptera with the antennae 

 fashioned after various types {Heterocera). It is then, with rare excep- 

 tions, dark-brown in colour. 



The pupa is plainly divisible into three well-marked and dissimilar 

 regions, head, thorax, and abdomen. The head is globular and deflexed. 

 The long antennae take origin from it laterally, and are bent backwards 

 ventrally and towards the middle line. A lunate convexity below and in 

 front of the base of the antennae marks the eye. A small median square 

 piece in front is the labrum, and the angle projecting forwards from the 

 convex surface that bears the eye, i.e. the gena, is formed under the larval 

 mandible. It touches the outer inferior angle of the labrum. The pupal 

 maxillae are large in size, and take origin below the labrum. Each has at its 

 cephalic extremity a horn-like projection, the two projections uniting in the 

 middle line. These projections usually but wrongly identified with the whole 

 tongue, antliae, or maxillae of the imago, are absent in some Sphingidae, e. g. 

 Aclierontia, Macroglossa, and of great size in others, e.g. Sphinx Convolvuli. 



