70 Osten Sacken: on the atavic index-tfiaracters 



as well as describers. This was perhaps the very reason why I be- 

 came interested in it, especially in the Tipulidaebrevipalpi. Their 

 Classification was, forty years ago, at the beginning of my entomo- 

 logical career, in the most primitive condition. The following State- 

 ment will give an idea of the State in which I found it. Two years 

 before my earliest entomological publication (Stettiner Ent. Zeitung 

 1854) the tenth volume of Zetterstedt's „Diptera Scandinaviae" 

 had appeared (in 1852), in which the author accepted the genus 

 Limnobia in Meigen's sense, and distributed the species among 

 eleven (unnamed) subdivisions. One of these subdivisions contained 

 fourteen species. They were so ill-matched that in my Classification 

 they had to be distributed among six sections of the seven which I 

 adopted for the Tipulidae brevipalpi (compare Mon. N.-A. Dipt, 

 Vol. IV, p. 21). As I said abovc, my Classification was published in 

 1859, and later, in a much enlarged edition, in 1869. These two 

 works principally concerned the North-American fauna. Since then, 

 up to 1887, I published several papers in which Tipulidae from 

 other parts of the world were taken into consideration. 



Thus my distribution, originally based upon a small North- 

 American material, has been in Operation now for thirty-five years, 

 and has been found applicable in all parts of the world. Schiner 

 adopted it in his Fauna Austriaca and, recently, Skuse for the 

 Australian fauna. — 



What Struck nie most, at that time, as well as some years later, 

 when I camc to apply this Classification to abnormal tropical forms, 

 or to anomalous native ones, was the great usefulness of the spurs 

 at the end of the tibiae and of the empodia for the characteri- 

 zation of the larger divisions, which I called sections. I found 

 them, whether present or absent, the most persistent of characters, 

 in spite of great modifications, for adaptive purposes, of other organs. 

 Reduced to the smallest proportions, and apparcntly as uscless as 

 the proverbial tail-buttons on our coats, they play their part as 

 phylogenetic indexes of descent and affinity. 



The three prineipal sections of the genuine brevipalpi, may be 

 distinguished, in the great majority of cases, by the use of this simple 

 formula (compare I.e. 1859, p. 199): 



I. No distinet empodia, no spurs at the tip of the tibiae: 



Lim no bin a. 



„ T , ,. ,. . I Tibiae with spurs: . . . Limnophilina. 

 II. Lmpodia distinet!™., . ... . ,. . . „.' 



Ilibiae without spurs: . . . krioptcniia. 



