148 Wisconsin Academy of Sciences, Arts , and Letters. 
Arrenurus Mulleri Koenike, 
Arrenurus securiformis Piersig (= A. festivus Koen. = 
A. buccinator Koch and Kramer), 
Arrenurus Soari George, 
Arrenurus Stjordaliensis Thor (var. A. caudatus ), 
Arrenurus tubulator Miiller (— A. medio-rotundus Thor), 
Arrenurus Zachariae Koenike. 
T’en species of Arrenuri belonging to the subgenus Megalurus 
were collected, five of which appear to he new. The results of 
the study of this material will now be considered. 
Arrenurus globator (Miiller). 
Fig. 1, ar—e, Pis. XIV—XV. 
Arrenurus globator Henman, 1879; S. 88, Fig. 2, Tab. X. 
Arrenurus globator Haller, 1882; S. 44. 
Arrenurus globator Barrios et Moniez, 1887; S. 24-25. 
Arrenurus globator Koenike, 1893; S. 12-16, Taf. I, Fig. 
11 - 12 . 
Arrenurus globator Koenike, 1894 (a) ; S. 260. 
Arrenurus globator Protz, 1895; S. 265. 
Arrenurus globator Piersig, 1896 (b) ; S. 58. 
Arrenurus globator Koenike, 1896; S. 212. 
Arrenurus globator Pisarovic, 1896; S. 3. 
Arrenurus globator Piersig, 1897; S. 279, Taf. XXVIII, 
Fig. 72. 
Arrenurus globator Croneberg, 1899; Xr. 27, Fig. 26. 
Arrenurus globator Thon, 1900; S. 108, Fig. 2, 6. 
Arrenurus globator Piersig, 1901; S. 82, Fig. 18. 
This is the most widely distributed and abundant of the 
Arrenuri collected; consequently it has been, possible to study 
a large amjount of material. It was one of the earliest forms 
described and one very widely mentioned in the accounts of all 
hydrachnologists. It has been found in all parts of Europe 
where collections have been made, and it is reported from 
Africa. 
Arrenurus globator is characterized first by the long cylin¬ 
drical appendage, slightly constricted at the base all around. 
The posterior end, where it widens out a little, is rounded with 
