112 PSYCHE. (November-Dtctmber iSS.i. 



lraclie;il hrancliiac, slio\\ing thai the licatioiis interposed for the transmission 



branches of the tracheae end caecallv. of air from one system to the other. It 



In tliis case the branches are so few that is not easy, in the living; insect, to 



theii' terminations can be easilv made determine tiie ebb and How directly ; 



out. as the movements occur suiklenly. Iiave 



The importance of tlris anatomical their speed multiplied bv the degree of 



item depends on its bearing on the microscopic amplilication ; and hence 



functions of the whole tracheal system. we are able only to see the rhythmical 



The action of the tracheae is tidal ])eristaltic action, and are left to guess 



rather than bv peripheral capillary at its cause. We lind. liowever. the 



circulation. Here also tlie endings of muscular contractions and expansions 



the ramifications are foimd to harmon- of other parts of the body .synchroniz- 



ize with their internal terminations ing with the pulsations in the gills, and 



along the nervous and digestive tracts, thus explaining how the flux and reflux, 



and in other parts of the tissues which rather than a mere circulation of the 



thev snpplv. We never iiiid a double air, is tlie cause of its renewal. 



system of tracheae with capillary rami- Princeton. N. y.. is Dec. iSSj. 



THE SCREW-WORM FLY. COMPSOMrJA MACELLARIA. 



BY .S.^MUEL WENDELL WILLISTON. NEW HAVEN". CONN. 



In connection with Professor Snow's To these results. howe\er, Mr. J. Bigot, 



article on this ll\ ' it seems worth while of Paris, has recentlv taken exception, 



to give a brief s\nopsis of papers pub- in a note - on Professor Snow's paper. 



lished in the past few years by the able This author's penchant for making .syn- 



dipterologist of South America, Dr. E. onyms himself may perhaps have 



L. Arril)i'ilzaga, of Buenos Aires. From something to do with his wishing to 



bis studies he has ascertained no less than preserve species founded on inade- 



twenty-six diflerent specific names that quale groimds. His argument that "il 



this fly had receixed ! It is possible me semble ftnt liasardeux d'avancer 



that some of these names would applv to (jii^un sciile ct ini'nie espi^cc se 



distinct species were their types exam- retrouve, en permanence, depuis les 



intil. but it is a thankless task to endeav- contins de la Patagonie jusqu'au dcia 



or to make order out of the chaos in des provinces centrales de I'-Xnu'rique 



which Walker, Macquart. antl Robi- du .Nord. \i\ant indilll'remuient si;us 



nean-Desvoidv have involved the subject, les zones torrides. teniperees et moine 



and the result of .\rrib;'dzaga's thorough froides.'" is of little value, when the 



studies can with proprietv be adopted. 



- Bull. £oc. cnlom. France. 12 Sept. 1883. no. 17. p. 



Psyche, Mar.-Apr. 1883, v. 4, p. 27-30. i.S4-'55. 



