12 SOME SOI Nl INDIAN INSECTS, ETC. [CHAP. I. 



appendages. In some insects the cerci may be long, many-jointed 

 us. not unlike antennae, as in some Mantidae; in others (most 

 Ten may be quite short and comprise only a very small 



number of joints; whilst in the majority of insects they are quite 

 absent. In the Earwigs and Japygidae .1 pair of horny, hooked 

 pS is present at the end of the body. In many female insects 

 special organs for the deposition of eggs maj be presenl and these 

 may normally be concealed within the body, being extensile .it 

 will, or ma) be placed permanently outside the body, in which 

 latter case more especially the instrument is called an ovipositor 

 I. at. egg-placer). In some insects (eg., Ichneumonidas) the oviposi- 

 tor may be a narrow threadlike appendage longer than the whole 

 insect, or it may be broad and sword-shaped (e.g., Mecopoda elongata) 

 or provided with special digging appendages (e.g., Cicindelidae) 

 or other apparatus for the successful deposition of the eggs. The 

 tip of the body may also carry tufts of hair which are detached by 

 the female as .1 covering for the eg^s. 



The Nervous System. 



The Nervous System in insects is fairly simple in general 

 structure and consists of three divisions, (I) the cephalic system 

 or brain, (2) the ventral ganglionic cord with its branches, and (3) 

 ili- uervous system of the alimentary tract. The cephalic system 

 consists of two main masses, a larger and very complex one placed 

 above the oesophagus and hence called the supra-iesophageal 

 ganglion (Figure 2, Gs) and a smaller one, placed below the oeso- 

 phagus and therefore known .1- the snb-cesophageal ganglion 

 (Figure 2, Gst), these two ganglia being connected to one anothei 

 by a strip oi nerve-material passing on either side of the gullet. 

 I li. supra-cesophageal ganglion is connected with the nerves 

 running from the eyes, antennae, and other sense-organs of the 

 head, whilst the sub-cesophageal ganglion connects directlj with 

 the nerves of the mouth-parts. These two great ganglia, or 

 bunches of nerves, are intimately connected with the ventral 

 ganglionic cord which runs along the ventral side of the thorax 

 and abdomen (Figure 2.1, h, t. a 1. throwing out from the main 

 masses smaller nerves which run into the limbs and body. In the 

 more highly developed insects these ventral ganglia are reduced in 

 number and increased in size, being sometimes massed in the 

 thorax to form what may be called a thoracic brain ; but in the more 

 generalized types, the ganglia are smaller and more numerous. It 

 is usuall] the case that larvae show .1 more generalized type of 

 nervous system in this respect in comparison with the perfect 

 insects into which thev subsequent!} develop. The third division 



