170 INSECTA. 



two stout j^anglions, one on the esophagus and the other in the pectus, 

 between the first and second pair of legs, which give off two remark- 

 able cords, divided at their extremity into two or three filaments. He 

 could only perceive two biliary vessels. To this excellent Memoir 

 we refer the reader both for these details and those relative to the 

 organs of generation, and to the salivary apparatus discovered by its 

 author in these Insects. 



N.cinerea,!!.; Roes., Insect. lb., xxii. About eight lines in 

 length; cinereous; back of the abdomen red; tail rather shorter 

 than the body*. 



Ranatra, Fab. 



The Ranatrte only differ from the Nepae in the linear form of their 

 body, in their rostrum, which is directed forwards, and in their an- 

 terior legs, of which the coxae and thighs are elongated and slender. 



R, linearis; Nepa linearis, L.; Roes., lb., XXIII. An inch 



long; pale-cinereous, somewhat yellowish; tail as long as the 

 body. 



The tuft on its eggs consists of but two setae f . 



The others — Notonectides — have their two anterior legs simply 

 curved underneath, Avith thighs of an ordinary size, and the tarsi 

 pointed and densely ciliated, or similar to those of the posterior ones. 

 Their body is almost cylindrical or ovoid, and tolerably thick or less 

 depressed than in the preceding Insects. Their posterior legs are 

 densely ciliated, resemble oars, and are terminated by two very small 

 and rather indistinct hooks. They swim or row with great swiftness, 

 and freqviently while on their back. They compose the genus 



NoTONECTA, Lin., 

 Which has been divided in the following manner : 



CoRixA, Geoff. — SiGARA, Fab. 



Where the scutellum is wanting J; the rostrum is very short, tri- 

 angular, and transversely striated; the elytra are horizontal; the an- 

 terior legs are very short, and their tarsi formed of a single compressed 

 and ciliated joint; the otlier legs are elongated, and the two inter- 

 mediate ones are terminated by two very long hooks. 



C. striata; Notonecta striata, L. ; Roes., lb., XXIX. The 



largest specimens are about five lines in length ; dark brown 

 above, with numerous yellowish dots or little stripes ; head, legs, 

 and all underneath, yellowish §. 



* Add N.fusca, grossa, ruhra, nigra, macv.Jata, Fab, 



-f- For the remaining species see Fab., Syst. Ryng. 



+ The Notonecta minufissima, Fab., is the type of the genus Sigara of Leach — Lin. 

 Trans., XII. The anterior tarsi, as in Corixa, consist of one joint, but this Insect 

 is furnished with a scutellum. Its thorax is transversal, and body oval, and not linear 

 or cylindrical. 



§ For the other species see Fab., Syst. Ryng. 



