252 CLASS INSECTA. 



disagreeable and penetrating odour which they then exhale, 

 and which remains a long time on the fingers. They copulate 

 on the surface of the water. Sometimes they remain at the 

 bottom, fixed to the plants. It is there in all probability 

 that they conceal themselves to pass the winter. 



M. Leon Dufour has published, in the Annals of Natural 

 Science, some anatomical observations on these insects. The 

 narrow intestine is remarkable for its length. The ccecum is 

 not lateral like that of the dytisci. The genital male 

 organs diff*er from those of the other carnivora. 



G. Natator, Lin. Panz. Faun. Insect. Germ. III. 5 ; De 

 Geer. Insect. IV. xiii, 4. 19- Three lines in length, oval, 

 very smooth, very shining, of a black, bronzed above, black 

 underneath, and with fawn-coloured feet. The scutellum is 

 triangular, very pointed, a little longer than broad. The 

 elytra are rounded at the end, with small sunken points, 

 forming regular and longitudinal lines. 



The female lays her eggs on the aquatic plants. They 

 are very small, in the form of little cylinders, and of a white 

 a little yellowish. The larva has the body long, slender, 

 linear, and composed of thirteen rings, of which the first 

 three have each a pair of feet. The head large, in an elon- 

 gated oval, and very flatted, presents the same parts as those 

 of the larvae of the dytisci ; but here the fourth ring and the 

 following seven, have on each side a conical, membranous, 

 and flexible thread, and barbed at the edges. The twelfth 

 ring has four similar threads, but much larger, and more 

 directed backwards. Two very fine tracheae traverse the 

 whole length of tlie body, and receive from each thread an 

 arterial vessel. The last ring of the body is very small, and 

 terminated by four long and parallel crotchets. This larva 

 lives in the water, and proceeds from it in the commencement 

 of August, to pass into the nymph state. It forms, with a 

 matter which it derives from its body, and similar to grey 



