COLLEMBOLA OF MINNESOTA 27 



Genus Sminthurus Latreille 1804. 



Of the eleven species of Sminthurus taken in the state, 

 three are new to science and others new to the continent. 



In the genus are found several interesting modifications. 

 One species is an albino without ocelli and almost without pig- 

 ment, others are modified for a life on the water, and have their 

 furcula so specialized as to constitute the most efficient instru- 

 ment for leaping that nature could devise. The normal number 

 of ocelli is present in all our species excepting the above-men- 

 tioned albino ; though certain ocelli exhibit a tendency to dimin- 

 ish in size in some of the species. For greater convenience in 

 study, most authors have separated the Sminthuri into two 

 groups of species : I, Setosi, those covered with strong hairs 

 or setas; and II, Pilosi, those covered with fine, short hairs. The 

 latter group contains, as a rule, the smaller species, and the 

 former the larger ones. They are to be found in dark, slightly 

 moist situations, some of them even around and on the water. 

 Many of them occur under loose bark, among leaves and rubbish 

 in the woods, etc. They are remarkably spry, and challenge the 

 liveliest movements on the part of their would-be captors. 



Key to the Genus Sminthurus. 



1. a — Ant. IV distinctly ringed. 2. 



b. — Ant. IV not distinctly ringed. 7. 



2. a. — Eyes present, body dark, or at least well pigmented. 3. 

 b. — Eyes wanting, body white with small reddish-brown 



specks. Two outward-pointing spurs at distal end of 

 manubrium. Mucrones ^ as long as dentes. 



caecus, 49. 



3. a. — Furcula adapted for water leaping. Dentes with two 



rows of laterally developed bristles. Mucrones spoon- 

 like. 4. 

 b. — Furcula not adapted for water leaping. Mucrones nar- 

 row, grooved. 5. 



4. a. — Furcula fan-like, lateral bristles on dentes very long, 



especially on the inner side, mucrones not ribbed, broadest 

 at distal end. Back set with long bristles among the 

 shorter hairs. Length, 2 mm. spinatus, 57. 



