COLEOPTERA. 425 



number of abdominal segments is ten, no more than nine have 

 been traced in the Coleoptera. 



A few genera are capable of producing sounds by rubbing 

 the limbs or elytra over finely wrinkled surfaces, which in 

 Trox are situated on the side of the basal segments of the ab- 

 domen, and in Strategus on the tergum of the penultimate seg- 

 ment of the abdomen, while such a surface is found in Ligyrus 

 on the surface of the elytra. 



The nervous system is subject to great variation in the Cole- 

 optera. The ganglia may be fused into three principal mas- 

 ses, as in the Lamellicorns, Curculionidcc and Scolytidce, 

 where the first mass corresponds to the prothoracic ganglia, 

 the second and larger to the second and third thoracic ganglia, 

 usually separated in the other suborders, while the third oblong 

 mass represents the whole number of abdominal ganglia, from 

 which radiate the nerves which are distributed to the muscles 

 of the abdomen and the reproductive system. In the Cist el- 

 id ce, (Edemeridce and Cerambycidce, the abdominal por- 

 tion of the nervous cord occupies the whole body, and there 

 are five ganglia in the abdomen. These two types of the ner- 

 vous cord sometimes run into each, but are always distinct in 

 the larva state. 



The alimentaiy canal is very simple in the flesh-eating spe- 

 cies, going directly, without many convolutions to the anus, 

 but in the vegetable feeders it is very long and greatly con- 

 voluted. The gizzard is oval in shape, its internal folds being 

 armed with hooks. There are two salivary glands. The urin- 

 ary tabes are either four or six in number. 



" The phosphorescent organs of the Lampyridce and cer- 

 tain E later idee consist of a mass of spherical cells, filled 

 with a finely granular substance and surrounded by numer- 

 ous tracheau branches. This substance which, by daylight, 

 appears of a yellow, sulphur-like aspect, fills in the Lam- 

 2)yrid(e, a portion of the abdominal cavity, and shines on the 

 ventral surface through the last abdominal segments, which are 

 covered with a very thin skin ; while with the Elateridce, the 

 illumination occurs through two transparent spots, situated on 

 the dorsal surface of the prothorax. The light produced by 

 these organs, so remarkably rich in tracheae, is undoubtedly the 



