STATES OF INSECTS. 249 



Ctenocera pectinicornis is armed with several strong co- 

 nical spines, pointing mostly towards the tail, which is 

 likewise the case with that of Tipula lunata a . As the 

 above pupae are usually subterranean or subcortical, the 

 spines assist in pushing them out of the ground, &c. 

 The respiratory horns that proceed from the thorax of 

 the pupae of many of the aquatic gnats will be noticed 

 in another place. Those of Corethra culiciformis and of 

 some other aquatic gnat-like Diptera, have their anus 

 furnished with a pair of oars, or natatory laminae, by 

 which they rise to the surface b . 



The figure of obtected pupae, or chrysalises, is more 

 uniform. They are commonly obtuse at the anterior ex- 

 tremity, and gradually contracted to a point at the poste- 

 rior, or tail. The outline usually inclines to a long oval 

 or an ellipse ; but in some, as Attacus Io and Luna, the 

 pupa is shorter and more spherical. In Geometra sam- 

 bucaria it represents an elongated cone, and in Hepialus 

 it is nearly cylindrical. In the butterfly tribe [Papilio L.) 

 the outline is frequently rendered angular by various pro- 

 tuberances. 



In all these pupae may be distinguished the following 

 parts :— ^first, the Head-case (Cephalo-theca), or anterior 

 extremity; secondly, the Trunk-case [Cyto-theca), or inter- 

 mediate part; and thirdly, the Abdomen-case [Gastro- 

 theca). 



1. The Head-case covers and protects the head of the 

 inclosed imago. From its sides behind proceed the an- 



a Reaum. v. i. ii./. 7- The anal and ventral spines of Tipula re- 

 ■plicata are also remarkable. De Geer vi. t. xx./. 14. 



b De Geer Ibid. 377. t. xxiii,/. 8, 9. n. Reaum. v. 42. t, vi./. 9. m n. 



