34 INSECTA. 
M. Leon Dufour, in the Reventh volume of the Animales Géné- 
rales des Sciences Physiques, has published some very curious ob- 
servations on the anatomy of the Ranatra linearis, and of the Nepa 
cinerea. He has discovered in these Insects a peculiar organ which 
he considers as a kind of pectoral trachea communicating with the | 
ordinary trachee. In the first it forms a pair of beautiful tufts of a 
nacre-white, and is composed of numerous ramusculi which are di- 
rected round a multiplex axis. It is situated in the midst of the 
muscular masses ofthe pectus. The pectoral trachez of the Nepa 
cinerea appeared to exluibit the vestiges of a pulmonary organ. 
They consist of two oblong bodies situated immediately under the 
region of the scutellum, invested by a fine, smooth, satin-white 
membrane. They are almost as long as the pectus, and, except at 
the two ends, free. They are filled with a kind of tow which when. 
examined under the microscope presents a homogeneous tissue formed 
of vascular arbusculi. The nervous system appeared to him to con- 
sist of two stout ganglions, one on the esophagus and the other in 
the pectus, between the first and second pair of legs, which give off 
two remarkable cords divided at their extremity into two or three 
filaments. He could only perceive two biliary vessels. To this ex- 
cellent 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, L.; Rees., Insect. Ib., xxii. About eight lines in 
lengths; cinereous; back of the abdomen red; tail rather shorter 
than the body(1). 
RanatTra, Fab. 
The Ranatre only differ from the Nepz in the linear form of their 
body, in their rostrum, which is directed forwards, and in their an- 
terior legs, of which the coxe and thighs are elongated and slender. 
R. linearis; Nepa linearis, L.; Rees.; Ib. XXIII. An inch 
long; pale-cinereous, somewhat yellowish; tail as long as the 
body. : 
The tuft on its eggs consists of but two setz(2). 
The others—Notonectides—have their two anterior legs simply 
curved underneath, with thighs of an ordinary size, and the tarsi 
pointed and densely ciliated, or similar to those of the posterior 
(1) Add WV. fusca, grossa, rubra, nigra, maculata, Fab. 
(2) For the remaining species, see Fab., Syst. Ryng. 
