A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . ch are retrograde Thysanura, there are fromone (Smynthurus), to three or four ventral ganglia. In the winged insects, where the ganglia are more or less fused,the fusion taking place in the head and at the end of the abdomen;there are in the more simple and generalized forms, such as Ephemera,the grasshopper, locusts (Fig. 240), etc., thirteen ganglia besides thetwo pairs of compound ganglia in
A text-book of entomology, including the anatomy, physiology, embryology and metamorphoses of insects, for use in agricultural and technical schools and colleges as well as by the working entomologist . ch are retrograde Thysanura, there are fromone (Smynthurus), to three or four ventral ganglia. In the winged insects, where the ganglia are more or less fused,the fusion taking place in the head and at the end of the abdomen;there are in the more simple and generalized forms, such as Ephemera,the grasshopper, locusts (Fig. 240), etc., thirteen ganglia besides thetwo pairs of compound ganglia in the head, three pairs of thoracic FUSION OF THE VENTRAL GANGLIA 225 ganglia, and usually from five to eight pairs of ganglia in theabdomen. In certain winged insects the process of fusion or degenerationis carried to such an extreme that there are either no abdominalganglia (Fig. 242, D), or their vestiges are situated in the thoraxand partially fused with the thoracic ones, as in the May beetle, inwhich the prothoracic pair of ganglia is separate, while the twoother thoracic ganglia are fused with the abdominal, the latter beingsituated in the thorax; this fusion is carried to a further extent. FIG. 243. — Nervous system of the May bee- FIG. 244. — The same of the stag-beetle, Lu- tle. Lachiiostermi fusoa: jc1, nerve to 1st, — camix damn, where there are 3 thoracic, and 3 to1, nerve to 2d, pair of wings ; ig, infraoesopha- separate abdominal ganglia,geal ganglion. than in any other Coleoptera yet examined. In many Diptera andHemiptera the abdominal ganglia are either absent or the vestigesare fused with the thoracic ganglia. Rhizotrogus, which is allied to our May beetle, as also Hydrometraand the Stylopidte are said to lack the suboesophageal ganglion(Brandt). In numerous Coleoptera (Acilius, Gyrinus, Necrophorus, Melo-lontha, Bostrichus, Rhynchtenus); in many Diptera (Culex, 226 TEXT-BOOK OF ENTOMOLOGY Asilus, Xylophaga, and Phora); and in the higher Hyrneuop
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectinsects
